diff --git a/NAMESPACE b/NAMESPACE
index 67c7a4941a..3dbc9d5ca6 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -422,6 +422,7 @@ export(get_alt_text)
 export(get_element_tree)
 export(get_guide_data)
 export(gg_dep)
+export(ggpar)
 export(ggplot)
 export(ggplotGrob)
 export(ggplot_add)
diff --git a/NEWS.md b/NEWS.md
index cd39c0b8ad..dcd22bdd8d 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,8 @@
 # ggplot2 (development version)
 
+* New helper function `ggpar()` to translate ggplot2's interpretation of 
+  graphical parameters to {grid}'s interpretation (@teunbrand, #5866).
+
 # ggplot2 3.5.1
 
 This is a small release focusing on fixing regressions from 3.5.0 and 
diff --git a/R/annotation-logticks.R b/R/annotation-logticks.R
index 8f3e8a63c2..1d25332a91 100644
--- a/R/annotation-logticks.R
+++ b/R/annotation-logticks.R
@@ -175,14 +175,14 @@ GeomLogticks <- ggproto("GeomLogticks", Geom,
         ticks$x_b <- with(data, segmentsGrob(
           x0 = unit(xticks$x, "native"), x1 = unit(xticks$x, "native"),
           y0 = unit(xticks$start, "cm"), y1 = unit(xticks$end, "cm"),
-          gp = gpar(col = alpha(colour, alpha), lty = linetype, lwd = linewidth * .pt)
+          gp = ggpar(col = alpha(colour, alpha), lty = linetype, lwd = linewidth)
         ))
       }
       if (grepl("t", sides) && nrow(xticks) > 0) {
         ticks$x_t <- with(data, segmentsGrob(
           x0 = unit(xticks$x, "native"), x1 = unit(xticks$x, "native"),
           y0 = unit(1, "npc") - unit(xticks$start, "cm"), y1 = unit(1, "npc") - unit(xticks$end, "cm"),
-          gp = gpar(col = alpha(colour, alpha), lty = linetype, lwd = linewidth * .pt)
+          gp = ggpar(col = alpha(colour, alpha), lty = linetype, lwd = linewidth)
         ))
       }
     }
@@ -213,14 +213,14 @@ GeomLogticks <- ggproto("GeomLogticks", Geom,
         ticks$y_l <- with(data, segmentsGrob(
           y0 = unit(yticks$y, "native"), y1 = unit(yticks$y, "native"),
           x0 = unit(yticks$start, "cm"), x1 = unit(yticks$end, "cm"),
-          gp = gpar(col = alpha(colour, alpha), lty = linetype, lwd = linewidth * .pt)
+          gp = ggpar(col = alpha(colour, alpha), lty = linetype, lwd = linewidth)
         ))
       }
       if (grepl("r", sides) && nrow(yticks) > 0) {
         ticks$y_r <- with(data, segmentsGrob(
           y0 = unit(yticks$y, "native"), y1 = unit(yticks$y, "native"),
           x0 = unit(1, "npc") - unit(yticks$start, "cm"), x1 = unit(1, "npc") - unit(yticks$end, "cm"),
-          gp = gpar(col = alpha(colour, alpha), lty = linetype, lwd = linewidth * .pt)
+          gp = ggpar(col = alpha(colour, alpha), lty = linetype, lwd = linewidth)
         ))
       }
     }
diff --git a/R/annotation-map.R b/R/annotation-map.R
index 86fd0e0952..2e53b3b9c2 100644
--- a/R/annotation-map.R
+++ b/R/annotation-map.R
@@ -95,9 +95,9 @@ GeomAnnotationMap <- ggproto("GeomAnnotationMap", GeomMap,
 
     polygonGrob(coords$x, coords$y, default.units = "native",
       id = grob_id,
-      gp = gpar(
+      gp = ggpar(
         col = data$colour, fill = alpha(data$fill, data$alpha),
-        lwd = data$linewidth * .pt)
+        lwd = data$linewidth)
       )
   },
 
diff --git a/R/coord-radial.R b/R/coord-radial.R
index 62b3bff136..89c84dd5dc 100644
--- a/R/coord-radial.R
+++ b/R/coord-radial.R
@@ -326,8 +326,8 @@ CoordRadial <- ggproto("CoordRadial", Coord,
         y = c(Inf, -Inf, -Inf,  Inf)
       )
       background <- coord_munch(self, background, panel_params, is_closed = TRUE)
-      bg_gp <- gpar(
-        lwd = len0_null(bg_element$linewidth * .pt),
+      bg_gp <- ggpar(
+        lwd = bg_element$linewidth,
         col = bg_element$colour, fill = bg_element$fill,
         lty = bg_element$linetype
       )
diff --git a/R/coord-sf.R b/R/coord-sf.R
index 331ca4f1f0..12f7371003 100644
--- a/R/coord-sf.R
+++ b/R/coord-sf.R
@@ -326,9 +326,9 @@ CoordSf <- ggproto("CoordSf", CoordCartesian,
     if (inherits(el, "element_blank")) {
       grobs <- list(element_render(theme, "panel.background"))
     } else {
-      line_gp <- gpar(
+      line_gp <- ggpar(
         col = el$colour,
-        lwd = len0_null(el$linewidth * .pt),
+        lwd = el$linewidth,
         lty = el$linetype
       )
       grobs <- c(
diff --git a/R/geom-curve.R b/R/geom-curve.R
index a2597a8d72..7ef935caeb 100644
--- a/R/geom-curve.R
+++ b/R/geom-curve.R
@@ -57,10 +57,10 @@ GeomCurve <- ggproto("GeomCurve", GeomSegment,
       default.units = "native",
       curvature = curvature, angle = angle, ncp = ncp,
       square = FALSE, squareShape = 1, inflect = FALSE, open = TRUE,
-      gp = gpar(
+      gp = ggpar(
         col = alpha(trans$colour, trans$alpha),
         fill = alpha(arrow.fill, trans$alpha),
-        lwd = trans$linewidth * .pt,
+        lwd = trans$linewidth,
         lty = trans$linetype,
         lineend = lineend),
       arrow = arrow
diff --git a/R/geom-dotplot.R b/R/geom-dotplot.R
index d79e6a823e..cdbc137fe7 100644
--- a/R/geom-dotplot.R
+++ b/R/geom-dotplot.R
@@ -293,9 +293,9 @@ GeomDotplot <- ggproto("GeomDotplot", Geom,
       dotstackGrob(stackaxis = stackaxis, x = tdata$x, y = tdata$y, dotdia = dotdianpc,
                   stackposition = tdata$stackpos, stackdir = stackdir, stackratio = stackratio,
                   default.units = "npc",
-                  gp = gpar(col = alpha(tdata$colour, tdata$alpha),
+                  gp = ggpar(col = alpha(tdata$colour, tdata$alpha),
                             fill = fill_alpha(tdata$fill, tdata$alpha),
-                            lwd = tdata$stroke, lty = tdata$linetype,
+                            lwd = tdata$stroke / .pt, lty = tdata$linetype,
                             lineend = lineend))
     )
   },
diff --git a/R/geom-hex.R b/R/geom-hex.R
index a220e12140..19076138dc 100644
--- a/R/geom-hex.R
+++ b/R/geom-hex.R
@@ -89,10 +89,10 @@ GeomHex <- ggproto("GeomHex", Geom,
 
     ggname("geom_hex", polygonGrob(
       coords$x, coords$y,
-      gp = gpar(
+      gp = ggpar(
         col = data$colour,
         fill = fill_alpha(data$fill, data$alpha),
-        lwd = data$linewidth * .pt,
+        lwd = data$linewidth,
         lty = data$linetype,
         lineend = lineend,
         linejoin = linejoin,
diff --git a/R/geom-label.R b/R/geom-label.R
index c292fa1a66..30ee6aa388 100644
--- a/R/geom-label.R
+++ b/R/geom-label.R
@@ -90,17 +90,17 @@ GeomLabel <- ggproto("GeomLabel", Geom,
         padding = label.padding,
         r = label.r,
         angle = row$angle,
-        text.gp = gpar(
+        text.gp = ggpar(
           col = row$colour,
           fontsize = row$size * size.unit,
           fontfamily = row$family,
           fontface = row$fontface,
           lineheight = row$lineheight
         ),
-        rect.gp = gpar(
+        rect.gp = ggpar(
           col = if (isTRUE(all.equal(label.size, 0))) NA else row$colour,
           fill = fill_alpha(row$fill, row$alpha),
-          lwd = label.size * .pt
+          lwd = label.size
         )
       )
     })
@@ -115,7 +115,7 @@ GeomLabel <- ggproto("GeomLabel", Geom,
 labelGrob <- function(label, x = unit(0.5, "npc"), y = unit(0.5, "npc"),
                       just = "center", padding = unit(0.25, "lines"), r = unit(0.1, "snpc"),
                       angle = NULL, default.units = "npc", name = NULL,
-                      text.gp = gpar(), rect.gp = gpar(fill = "white"), vp = NULL) {
+                      text.gp = gpar(), rect.gp = ggpar(fill = "white"), vp = NULL) {
 
   if (length(label) != 1) {
     cli::cli_abort("{.arg label} must be of length 1.")
@@ -130,7 +130,7 @@ labelGrob <- function(label, x = unit(0.5, "npc"), y = unit(0.5, "npc"),
     vp <- viewport(
       angle = angle, x = x, y = y,
       width = unit(0, "cm"), height = unit(0, "cm"),
-      gp = gpar(fontsize = text.gp$fontsize)
+      gp = ggpar(fontsize = text.gp$fontsize)
     )
     x <- unit(rep(0.5, length(x)), "npc")
     y <- unit(rep(0.5, length(y)), "npc")
diff --git a/R/geom-map.R b/R/geom-map.R
index 01024ebeff..8086db6209 100644
--- a/R/geom-map.R
+++ b/R/geom-map.R
@@ -144,10 +144,10 @@ GeomMap <- ggproto("GeomMap", GeomPolygon,
     data <- data[data_rows, , drop = FALSE]
 
     polygonGrob(coords$x, coords$y, default.units = "native", id = grob_id,
-      gp = gpar(
+      gp = ggpar(
         col = data$colour,
         fill = fill_alpha(data$fill, data$alpha),
-        lwd = data$linewidth * .pt,
+        lwd = data$linewidth,
         lineend = lineend,
         linejoin = linejoin,
         linemitre = linemitre
diff --git a/R/geom-path.R b/R/geom-path.R
index ad7589a028..b705162b9f 100644
--- a/R/geom-path.R
+++ b/R/geom-path.R
@@ -200,10 +200,10 @@ GeomPath <- ggproto("GeomPath", Geom,
       segmentsGrob(
         munched$x[!end], munched$y[!end], munched$x[!start], munched$y[!start],
         default.units = "native", arrow = arrow,
-        gp = gpar(
+        gp = ggpar(
           col = alpha(munched$colour, munched$alpha)[!end],
           fill = alpha(munched$colour, munched$alpha)[!end],
-          lwd = munched$linewidth[!end] * .pt,
+          lwd = munched$linewidth[!end],
           lty = munched$linetype[!end],
           lineend = lineend,
           linejoin = linejoin,
@@ -215,10 +215,10 @@ GeomPath <- ggproto("GeomPath", Geom,
       polylineGrob(
         munched$x, munched$y, id = id,
         default.units = "native", arrow = arrow,
-        gp = gpar(
+        gp = ggpar(
           col = alpha(munched$colour, munched$alpha)[start],
           fill = alpha(munched$colour, munched$alpha)[start],
-          lwd = munched$linewidth[start] * .pt,
+          lwd = munched$linewidth[start],
           lty = munched$linetype[start],
           lineend = lineend,
           linejoin = linejoin,
diff --git a/R/geom-point.R b/R/geom-point.R
index 20a7f46b58..0de4a68173 100644
--- a/R/geom-point.R
+++ b/R/geom-point.R
@@ -145,18 +145,15 @@ GeomPoint <- ggproto("GeomPoint", Geom,
     }
 
     coords <- coord$transform(data, panel_params)
-    stroke_size <- coords$stroke
-    stroke_size[is.na(stroke_size)] <- 0
     ggname("geom_point",
       pointsGrob(
         coords$x, coords$y,
         pch = coords$shape,
-        gp = gpar(
+        gp = ggpar(
           col = alpha(coords$colour, coords$alpha),
           fill = fill_alpha(coords$fill, coords$alpha),
-          # Stroke is added around the outside of the point
-          fontsize = coords$size * .pt + stroke_size * .stroke / 2,
-          lwd = coords$stroke * .stroke / 2
+          pointsize = coords$size,
+          stroke = coords$stroke
         )
       )
     )
diff --git a/R/geom-polygon.R b/R/geom-polygon.R
index c644d9daad..3cdce9b53e 100644
--- a/R/geom-polygon.R
+++ b/R/geom-polygon.R
@@ -130,10 +130,10 @@ GeomPolygon <- ggproto("GeomPolygon", Geom,
         polygonGrob(
           munched$x, munched$y, default.units = "native",
           id = munched$group,
-          gp = gpar(
+          gp = ggpar(
             col = first_rows$colour,
             fill = fill_alpha(first_rows$fill, first_rows$alpha),
-            lwd = first_rows$linewidth * .pt,
+            lwd = first_rows$linewidth,
             lty = first_rows$linetype,
             lineend = lineend,
             linejoin = linejoin,
@@ -161,10 +161,10 @@ GeomPolygon <- ggproto("GeomPolygon", Geom,
           munched$x, munched$y, default.units = "native",
           id = id, pathId = munched$group,
           rule = rule,
-          gp = gpar(
+          gp = ggpar(
             col = first_rows$colour,
             fill = fill_alpha(first_rows$fill, first_rows$alpha),
-            lwd = first_rows$linewidth * .pt,
+            lwd = first_rows$linewidth,
             lty = first_rows$linetype,
             lineend = lineend,
             linejoin = linejoin,
diff --git a/R/geom-rect.R b/R/geom-rect.R
index d39978897a..cfd39dab4a 100644
--- a/R/geom-rect.R
+++ b/R/geom-rect.R
@@ -57,10 +57,10 @@ GeomRect <- ggproto("GeomRect", Geom,
         height = coords$ymax - coords$ymin,
         default.units = "native",
         just = c("left", "top"),
-        gp = gpar(
+        gp = ggpar(
           col = coords$colour,
           fill = fill_alpha(coords$fill, coords$alpha),
-          lwd = coords$linewidth * .pt,
+          lwd = coords$linewidth,
           lty = coords$linetype,
           linejoin = linejoin,
           lineend = lineend
diff --git a/R/geom-ribbon.R b/R/geom-ribbon.R
index d93df77850..11774c97f5 100644
--- a/R/geom-ribbon.R
+++ b/R/geom-ribbon.R
@@ -182,10 +182,10 @@ GeomRibbon <- ggproto("GeomRibbon", Geom,
     g_poly <- polygonGrob(
       munched_poly$x, munched_poly$y, id = munched_poly$id,
       default.units = "native",
-      gp = gpar(
+      gp = ggpar(
         fill = fill_alpha(aes$fill, aes$alpha),
         col = if (is_full_outline) aes$colour else NA,
-        lwd = if (is_full_outline) aes$linewidth * .pt else 0,
+        lwd = if (is_full_outline) aes$linewidth else 0,
         lty = if (is_full_outline) aes$linetype else 1,
         lineend = lineend,
         linejoin = linejoin,
@@ -213,9 +213,9 @@ GeomRibbon <- ggproto("GeomRibbon", Geom,
     g_lines <- polylineGrob(
       munched_lines$x, munched_lines$y, id = munched_lines$id,
       default.units = "native",
-      gp = gpar(
+      gp = ggpar(
         col = aes$colour,
-        lwd = aes$linewidth * .pt,
+        lwd = aes$linewidth,
         lty = aes$linetype,
         lineend = lineend,
         linejoin = linejoin,
diff --git a/R/geom-rug.R b/R/geom-rug.R
index 0fe393bb95..cda6a01bc4 100644
--- a/R/geom-rug.R
+++ b/R/geom-rug.R
@@ -108,10 +108,10 @@ GeomRug <- ggproto("GeomRug", Geom,
       list(min = -1 * length, max = unit(1, "npc") + length)
     }
 
-    gp <- gpar(
+    gp <- ggpar(
       col = alpha(data$colour, data$alpha),
       lty = data$linetype,
-      lwd = data$linewidth * .pt,
+      lwd = data$linewidth,
       lineend = lineend
     )
     if (!is.null(data$x)) {
diff --git a/R/geom-segment.R b/R/geom-segment.R
index f32b61f876..9a4de4dbb3 100644
--- a/R/geom-segment.R
+++ b/R/geom-segment.R
@@ -122,10 +122,10 @@ GeomSegment <- ggproto("GeomSegment", Geom,
       arrow.fill <- arrow.fill %||% coord$colour
       return(segmentsGrob(coord$x, coord$y, coord$xend, coord$yend,
         default.units = "native",
-        gp = gpar(
+        gp = ggpar(
           col = alpha(coord$colour, coord$alpha),
           fill = alpha(arrow.fill, coord$alpha),
-          lwd = coord$linewidth * .pt,
+          lwd = coord$linewidth,
           lty = coord$linetype,
           lineend = lineend,
           linejoin = linejoin
diff --git a/R/geom-text.R b/R/geom-text.R
index acfbb0337a..ea996cb040 100644
--- a/R/geom-text.R
+++ b/R/geom-text.R
@@ -239,7 +239,7 @@ GeomText <- ggproto("GeomText", Geom,
       data$x, data$y, default.units = "native",
       hjust = data$hjust, vjust = data$vjust,
       rot = data$angle,
-      gp = gpar(
+      gp = ggpar(
         col = alpha(data$colour, data$alpha),
         fontsize = data$size * size.unit,
         fontfamily = data$family,
diff --git a/R/guide-colorbar.R b/R/guide-colorbar.R
index b8e62f82c9..6d90f13a82 100644
--- a/R/guide-colorbar.R
+++ b/R/guide-colorbar.R
@@ -379,7 +379,7 @@ GuideColourbar <- ggproto(
         vjust = 0, hjust = 0,
         width = width, height = height,
         default.units = "npc",
-        gp = gpar(col = NA, fill = decor$colour)
+        gp = ggpar(col = NA, fill = decor$colour)
       )
     } else if (params$display == "gradient") {
       check_device("gradients", call = expr(guide_colourbar()))
@@ -394,7 +394,7 @@ GuideColourbar <- ggproto(
         vertical   = list(x1 = unit(0.5, "npc"), x2 = unit(0.5, "npc"))
       )
       gradient <- inject(linearGradient(decor$colour, value, !!!position))
-      grob <- rectGrob(gp = gpar(fill = gradient, col = NA))
+      grob <- rectGrob(gp = ggpar(fill = gradient, col = NA))
     }
 
     frame <- element_grob(elements$frame, fill = NA)
diff --git a/R/guide-colorsteps.R b/R/guide-colorsteps.R
index d85421bbc9..cd21dce6a4 100644
--- a/R/guide-colorsteps.R
+++ b/R/guide-colorsteps.R
@@ -204,7 +204,7 @@ GuideColoursteps <- ggproto(
 
     size <- abs(decor$max - decor$min)
     just <- as.numeric(decor$min > decor$max)
-    gp   <- gpar(col = NA, fill = decor$colour)
+    gp   <- ggpar(col = NA, fill = decor$colour)
     if (params$direction == "vertical") {
       grob <- rectGrob(
         x = 0, y = decor$min,
diff --git a/R/legend-draw.R b/R/legend-draw.R
index f1de0b80e5..ce16f7a6ab 100644
--- a/R/legend-draw.R
+++ b/R/legend-draw.R
@@ -31,16 +31,13 @@ draw_key_point <- function(data, params, size) {
   }
 
   # NULL means the default stroke size, and NA means no stroke.
-  stroke_size <- data$stroke %||% 0.5
-  stroke_size[is.na(stroke_size)] <- 0
-
   pointsGrob(0.5, 0.5,
     pch = data$shape,
-    gp = gpar(
+    gp = ggpar(
       col = alpha(data$colour %||% "black", data$alpha),
       fill = fill_alpha(data$fill %||% "black", data$alpha),
-      fontsize = (data$size %||% 1.5) * .pt + stroke_size * .stroke / 2,
-      lwd = stroke_size * .stroke / 2
+      pointsize = data$size %||% 1.5,
+      stroke = data$stroke %||% 0.5
     )
   )
 }
@@ -49,9 +46,9 @@ draw_key_point <- function(data, params, size) {
 #' @rdname draw_key
 draw_key_abline <- function(data, params, size) {
   segmentsGrob(0, 0, 1, 1,
-    gp = gpar(
+    gp = ggpar(
       col = alpha(data$colour %||% data$fill %||% "black", data$alpha),
-      lwd = (data$linewidth %||% 0.5) * .pt,
+      lwd = data$linewidth %||% 0.5,
       lty = data$linetype %||% 1,
       lineend = params$lineend %||% "butt"
     )
@@ -61,7 +58,7 @@ draw_key_abline <- function(data, params, size) {
 #' @export
 #' @rdname draw_key
 draw_key_rect <- function(data, params, size) {
-  rectGrob(gp = gpar(
+  rectGrob(gp = ggpar(
     col = NA,
     fill = fill_alpha(data$fill %||% data$colour %||% "grey20", data$alpha),
     lty = data$linetype %||% 1
@@ -79,11 +76,11 @@ draw_key_polygon <- function(data, params, size) {
   rectGrob(
     width = unit(1, "npc") - unit(lwd, "mm"),
     height = unit(1, "npc") - unit(lwd, "mm"),
-    gp = gpar(
+    gp = ggpar(
       col = data$colour %||% NA,
       fill = fill_alpha(data$fill %||% "grey20", data$alpha),
       lty = data$linetype %||% 1,
-      lwd = lwd * .pt,
+      lwd = lwd,
       linejoin = params$linejoin %||% "mitre",
       lineend = params$lineend %||% "butt"
   ))
@@ -98,10 +95,10 @@ draw_key_blank <- function(data, params, size) {
 #' @export
 #' @rdname draw_key
 draw_key_boxplot <- function(data, params, size) {
-  gp <- gpar(
+  gp <- ggpar(
     col = data$colour %||% "grey20",
     fill = fill_alpha(data$fill %||% "white", data$alpha),
-    lwd = (data$linewidth %||% 0.5) * .pt,
+    lwd = data$linewidth %||% 0.5,
     lty = data$linetype %||% 1,
     lineend = params$lineend %||% "butt",
     linejoin = params$linejoin %||% "mitre"
@@ -129,10 +126,10 @@ draw_key_boxplot <- function(data, params, size) {
 #' @export
 #' @rdname draw_key
 draw_key_crossbar <- function(data, params, size) {
-  gp <- gpar(
+  gp <- ggpar(
     col = data$colour %||% "grey20",
     fill = fill_alpha(data$fill %||% "white", data$alpha),
-    lwd = (data$linewidth %||% 0.5) * .pt,
+    lwd = data$linewidth %||% 0.5,
     lty = data$linetype %||% 1,
     lineend = params$lineend %||% "butt",
     linejoin = params$linejoin %||% "mitre"
@@ -161,11 +158,11 @@ draw_key_path <- function(data, params, size) {
     data$linetype[is.na(data$linetype)] <- 0
   }
   grob <- segmentsGrob(0.1, 0.5, 0.9, 0.5,
-    gp = gpar(
+    gp = ggpar(
       col = alpha(data$colour %||% data$fill %||% "black", data$alpha),
       fill = alpha(params$arrow.fill %||% data$colour
                    %||% data$fill %||% "black", data$alpha),
-      lwd = (data$linewidth %||% 0.5) * .pt,
+      lwd = data$linewidth %||% 0.5,
       lty = data$linetype %||% 1,
       lineend = params$lineend %||% "butt"
     ),
@@ -184,9 +181,9 @@ draw_key_path <- function(data, params, size) {
 #' @rdname draw_key
 draw_key_vpath <- function(data, params, size) {
   grob <- segmentsGrob(0.5, 0.1, 0.5, 0.9,
-    gp = gpar(
+    gp = ggpar(
       col = alpha(data$colour %||% data$fill %||% "black", data$alpha),
-      lwd = (data$linewidth %||% 0.5) * .pt,
+      lwd = data$linewidth %||% 0.5,
       lty = data$linetype %||% 1,
       lineend = params$lineend %||% "butt"
     ),
@@ -206,7 +203,7 @@ draw_key_vpath <- function(data, params, size) {
 draw_key_dotplot <- function(data, params, size) {
   pointsGrob(0.5, 0.5, size = unit(.5, "npc"),
     pch = 21,
-    gp = gpar(
+    gp = ggpar(
       col = alpha(data$colour %||% "black", data$alpha),
       fill = fill_alpha(data$fill %||% "black", data$alpha),
       lty = data$linetype %||% 1,
@@ -247,7 +244,7 @@ draw_key_smooth <- function(data, params, size) {
   path <- draw_key_path(data, params, size)
 
   grob <- grobTree(
-    if (isTRUE(params$se)) rectGrob(gp = gpar(col = NA, fill = data$fill)),
+    if (isTRUE(params$se)) rectGrob(gp = ggpar(col = NA, fill = data$fill)),
     path
   )
   attr(grob, "width") <- attr(path, "width")
@@ -268,7 +265,7 @@ draw_key_text <- function(data, params, size) {
     angle = data$angle,
     hjust = hjust,
     vjust = vjust,
-    gp = gpar(
+    gp = ggpar(
       col = alpha(data$colour %||% data$fill %||% "black", data$alpha),
       fontfamily = data$family   %||% "",
       fontface   = data$fontface %||% 1,
@@ -304,16 +301,16 @@ draw_key_label <- function(data, params, size) {
     just = c(hjust, vjust),
     padding = padding,
     r = params$label.r %||% unit(0.15, "lines"),
-    text.gp = gpar(
+    text.gp = ggpar(
       col = data$colour %||% "black",
       fontfamily = data$family   %||% "",
       fontface   = data$fontface %||% 1,
       fontsize   = (data$size %||% 3.88) * .pt
     ),
-    rect.gp = gpar(
+    rect.gp = ggpar(
       col  = if (isTRUE(all.equal(params$label.size, 0))) NA else data$colour,
       fill = alpha(data$fill %||% "white", data$alpha),
-      lwd  = params$label.size * .pt
+      lwd  = params$label.size
     )
   )
   angle  <- deg2rad(data$angle %||% 0)
@@ -331,9 +328,9 @@ draw_key_label <- function(data, params, size) {
 #' @rdname draw_key
 draw_key_vline <- function(data, params, size) {
   segmentsGrob(0.5, 0, 0.5, 1,
-    gp = gpar(
+    gp = ggpar(
       col = alpha(data$colour %||% data$fill %||% "black", data$alpha),
-      lwd = (data$linewidth %||% 0.5) * .pt,
+      lwd = data$linewidth %||% 0.5,
       lty = data$linetype %||% 1,
       lineend = params$lineend %||% "butt"
     )
@@ -352,9 +349,9 @@ draw_key_timeseries <- function(data, params, size) {
   grid::linesGrob(
     x = c(0, 0.4, 0.6, 1),
     y = c(0.1, 0.6, 0.4, 0.9),
-    gp = gpar(
+    gp = ggpar(
       col = alpha(data$colour %||% data$fill %||% "black", data$alpha),
-      lwd = (data$linewidth %||% 0.5) * .pt,
+      lwd = data$linewidth %||% 0.5,
       lty = data$linetype %||% 1,
       lineend = params$lineend %||% "butt",
       linejoin = params$linejoin %||% "round"
diff --git a/R/margins.R b/R/margins.R
index b563331002..c1ad607a21 100644
--- a/R/margins.R
+++ b/R/margins.R
@@ -124,9 +124,9 @@ titleGrob <- function(label, x, y, hjust, vjust, angle = 0, gp = gpar(),
       rectGrob(
         x = x, y = y, width = width, height = height,
         hjust = just$hjust, vjust = just$vjust,
-        gp = gpar(fill = "cornsilk", col = NA)
+        gp = ggpar(fill = "cornsilk", col = NA)
       ),
-      pointsGrob(x, y, pch = 20, gp = gpar(col = "gold")),
+      pointsGrob(x, y, pch = 20, gp = ggpar(col = "gold")),
       grob
     )
   } else {
@@ -193,7 +193,7 @@ justify_grobs <- function(grobs, x = NULL, y = NULL, hjust = 0.5, vjust = 0.5,
 
   if (isTRUE(debug)) {
     children <- gList(
-      rectGrob(gp = gpar(fill = "lightcyan", col = NA)),
+      rectGrob(gp = ggpar(fill = "lightcyan", col = NA)),
       grobs
     )
   }
@@ -219,7 +219,7 @@ justify_grobs <- function(grobs, x = NULL, y = NULL, hjust = 0.5, vjust = 0.5,
     #cat("E - hjust, vjust:", c(hjust, vjust), "\n")
     grobTree(
       result_grob,
-      pointsGrob(x, y, pch = 20, gp = gpar(col = "mediumturquoise"))
+      pointsGrob(x, y, pch = 20, gp = ggpar(col = "mediumturquoise"))
     )
   } else {
     result_grob
@@ -307,7 +307,7 @@ font_descent <- function(family = "", face = "plain", size = 12, cex = 1) {
   if (is.null(descent)) {
     descent <- convertHeight(grobDescent(textGrob(
       label = "gjpqyQ",
-      gp = gpar(
+      gp = ggpar(
         fontsize = size,
         cex = cex,
         fontfamily = family,
diff --git a/R/theme-elements.R b/R/theme-elements.R
index b8e83c75e4..41b989df7e 100644
--- a/R/theme-elements.R
+++ b/R/theme-elements.R
@@ -187,14 +187,6 @@ element_render <- function(theme, element, ..., name = NULL) {
   ggname(paste(element, name, sep = "."), grob)
 }
 
-
-# Returns NULL if x is length 0
-len0_null <- function(x) {
-  if (length(x) == 0)  NULL
-  else                 x
-}
-
-
 #' Generate grid grob from theme element
 #'
 #' @param element Theme element, i.e. `element_rect` or similar.
@@ -220,8 +212,8 @@ element_grob.element_rect <- function(element, x = 0.5, y = 0.5,
   }
 
   # The gp settings can override element_gp
-  gp <- gpar(lwd = len0_null(linewidth * .pt), col = colour, fill = fill, lty = linetype)
-  element_gp <- gpar(lwd = len0_null(element$linewidth * .pt), col = element$colour,
+  gp <- ggpar(lwd = linewidth, col = colour, fill = fill, lty = linetype)
+  element_gp <- ggpar(lwd = element$linewidth, col = element$colour,
     fill = element$fill, lty = element$linetype)
 
   rectGrob(x, y, width, height, gp = modify_list(element_gp, gp), ...)
@@ -244,10 +236,10 @@ element_grob.element_text <- function(element, label = "", x = NULL, y = NULL,
   angle <- angle %||% element$angle %||% 0
 
   # The gp settings can override element_gp
-  gp <- gpar(fontsize = size, col = colour,
+  gp <- ggpar(fontsize = size, col = colour,
     fontfamily = family, fontface = face,
     lineheight = lineheight)
-  element_gp <- gpar(fontsize = element$size, col = element$colour,
+  element_gp <- ggpar(fontsize = element$size, col = element$colour,
     fontfamily = element$family, fontface = element$face,
     lineheight = element$lineheight)
 
@@ -269,13 +261,13 @@ element_grob.element_line <- function(element, x = 0:1, y = 0:1,
   }
 
   # The gp settings can override element_gp
-  gp <- gpar(
+  gp <- ggpar(
     col = colour, fill = colour,
-    lwd = len0_null(linewidth * .pt), lty = linetype, lineend = lineend
+    lwd = linewidth, lty = linetype, lineend = lineend
   )
-  element_gp <- gpar(
+  element_gp <- ggpar(
     col = element$colour, fill = element$colour,
-    lwd = len0_null(element$linewidth * .pt), lty = element$linetype,
+    lwd = element$linewidth, lty = element$linetype,
     lineend = element$lineend
   )
   arrow <- if (is.logical(element$arrow) && !element$arrow) {
diff --git a/R/utilities-grid.R b/R/utilities-grid.R
index 389dad3eea..8efdee4d02 100644
--- a/R/utilities-grid.R
+++ b/R/utilities-grid.R
@@ -13,6 +13,38 @@ ggname <- function(prefix, grob) {
   grob
 }
 
+#' Interpreter for graphical parameters
+#'
+#' This is a wrapper for [`grid::gpar()`] that applies ggplot2's interpretation
+#' of graphical parameters.
+#'
+#' @param ... Named arguments passed on to `gpar()`.
+#' @param stroke Linewidth for points. Populates the `lwd` grid parameter.
+#' @param pointsize Size for points. Populates the `fontsize` grid parameter.
+#'
+#' @return An object of class 'gpar'.
+#' @keywords internal
+#' @export
+ggpar <- function(..., stroke = NULL, pointsize = NULL) {
+  args <- list2(...)
+  args <- args[lengths(args) > 0]
+
+  if (!is.null(args$lwd)) {
+    args$lwd <- args$lwd * .pt
+  }
+  if (!is.null(stroke)) {
+    args$lwd <- stroke * .stroke / 2
+  }
+  if (!is.null(pointsize)) {
+    # Stroke is added around the outside of the point
+    stroke <- stroke %||% 0
+    stroke[is.na(stroke)] <- 0
+    args$fontsize <- pointsize * .pt + stroke * .stroke / 2
+  }
+
+  inject(gpar(!!!args))
+}
+
 width_cm <- function(x) {
   if (is.grob(x)) {
     convertWidth(grobWidth(x), "cm", TRUE)
diff --git a/man/ggpar.Rd b/man/ggpar.Rd
new file mode 100644
index 0000000000..3186597d02
--- /dev/null
+++ b/man/ggpar.Rd
@@ -0,0 +1,23 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/utilities-grid.R
+\name{ggpar}
+\alias{ggpar}
+\title{Interpreter for graphical parameters}
+\usage{
+ggpar(..., stroke = NULL, pointsize = NULL)
+}
+\arguments{
+\item{...}{Named arguments passed on to \code{gpar()}.}
+
+\item{stroke}{Linewidth for points. Populates the \code{lwd} grid parameter.}
+
+\item{pointsize}{Size for points. Populates the \code{fontsize} grid parameter.}
+}
+\value{
+An object of class 'gpar'.
+}
+\description{
+This is a wrapper for \code{\link[grid:gpar]{grid::gpar()}} that applies ggplot2's interpretation
+of graphical parameters.
+}
+\keyword{internal}