A free online calculator for GNSS engineers. Convert between time scales, transform coordinates, and compute distances — instantly, in your browser.
Convert timestamps across every major GNSS and astronomical time scale in one place:
- GNSS times — GPS, Galileo, BeiDou, GLONASS
- Standard scales — UTC, TAI, TT, UNIX
- Astronomical dates — Julian Date, Modified Julian Date, MJD2000
- GPS-specific — Week number, Time of Week (TOW), RINEX format
- Calendar info — Day of year, week of year, hour code
- Time differences — Elapsed time between any two timestamps
- Live GPS clock — Current GPS time, week, and seconds updated in real time
All conversions are bidirectional. Change any field and every other field updates instantly. Leap seconds are handled automatically.
A full geodetic toolkit for coordinate conversion and spatial computations:
- Coordinate formats — ECEF, geodetic (lat/lon/height), DMS, UTM, Maidenhead grid locator, geohash
- Distances — Orthodromic (great-circle), loxodromic (rhumb line), and Euclidean, with bearings and midpoint
- Local frames — AER (Azimuth/Elevation/Range) and ENU (East/North/Up) from a reference position
- Horizon distance — Geometric line-of-sight distance from a given altitude
- Interactive map — Visualize positions, great-circle arcs, and distances on a Leaflet map
- Geolocation — Use your device location or search an address
- Shareable links — Positions are encoded in the URL so you can share or bookmark any result
All computations use the WGS84 ellipsoid with Vincenty's formulae for geodetic accuracy.
- No install, no sign-up — open the site and start calculating
- Everything runs in the browser — your data never leaves your device
- Instant feedback — all fields update as you type
- Copy any value — one-click copy on every computed result
- Mobile-friendly — works on any screen size
- Built by a GNSS engineer — designed around the computations you actually need every day
Astro + React · TypeScript · Tailwind CSS · gnss-js · Leaflet · Deployed on Cloudflare Workers
pnpm install
pnpm dev| Command | Description |
|---|---|
pnpm build |
Build for production |
pnpm preview |
Preview the production build |
pnpm format |
Format code with Prettier |
Miguel González — miguel.es