diff --git a/xarray/backends/api.py b/xarray/backends/api.py
index cfd3ff7fc0f..1fd75dbbfa5 100644
--- a/xarray/backends/api.py
+++ b/xarray/backends/api.py
@@ -1494,10 +1494,10 @@ def open_mfdataset(
     chunks : int, dict, 'auto' or None, optional
         Dictionary with keys given by dimension names and values given by chunk sizes.
         In general, these should divide the dimensions of each dataset. If int, chunk
-        each dimension by ``chunks``. By default, chunks will be chosen to load entire
-        input files into memory at once. This has a major impact on performance: please
-        see the full documentation for more details [2]_. This argument is evaluated
-        on a per-file basis, so chunk sizes that span multiple files will be ignored.
+        each dimension by ``chunks``. By default, chunks will be chosen to match the
+        chunks on disk. This may impact performance: please see the full documentation
+        for more details [2]_. This argument is evaluated on a per-file basis, so chunk
+        sizes that span multiple files will be ignored.
     concat_dim : str, DataArray, Index or a Sequence of these or None, optional
         Dimensions to concatenate files along.  You only need to provide this argument
         if ``combine='nested'``, and if any of the dimensions along which you want to