diff --git a/Lib/gzip.py b/Lib/gzip.py
index e422773b3edfb7..ba7b7ee140a53f 100644
--- a/Lib/gzip.py
+++ b/Lib/gzip.py
@@ -596,7 +596,7 @@ def main():
                 f = builtins.open(arg, "rb")
                 g = open(arg + ".gz", "wb")
         while True:
-            chunk = f.read(1024)
+            chunk = f.read(io.DEFAULT_BUFFER_SIZE)
             if not chunk:
                 break
             g.write(chunk)
diff --git a/Misc/NEWS.d/next/Library/2021-02-25-09-08-55.bpo-43317.qrOOpB.rst b/Misc/NEWS.d/next/Library/2021-02-25-09-08-55.bpo-43317.qrOOpB.rst
new file mode 100644
index 00000000000000..01ff48ad90d6b6
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-02-25-09-08-55.bpo-43317.qrOOpB.rst
@@ -0,0 +1,3 @@
+Set the chunk size for the ``gzip`` module main function to
+io.DEFAULT_BUFFER_SIZE. This is slightly faster than the 1024 bytes constant
+that was used previously.