diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0853ce0..10692ae 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,7 @@
 - Contacts: include birthdays in `contacts list` and `contacts search` text and JSON output. (#441)
 
 ### Fixed
+- Backup: split Gmail checkpoint commits into smaller encrypted shard files so large messages stay below GitHub's blob limit.
 - Calendar: display `calendar events` times and JSON local fields in the calendar timezone instead of preserving arbitrary event offsets. (#493)
 - Drive/Docs/Sheets/Slides: treat `--out -` as stdout for downloads and exports instead of creating `-`/`-.ext` files; reject `--json --out -` to keep byte streams parseable. (#286)
 - Docs: deprecate editing-command `--tab-id` in favor of `--tab`, and resolve tab titles to canonical tab IDs before mutations. (#533) — thanks @johnbenjaminlewis.
diff --git a/internal/cmd/backup_gmail.go b/internal/cmd/backup_gmail.go
index e616d4b..c314487 100644
--- a/internal/cmd/backup_gmail.go
+++ b/internal/cmd/backup_gmail.go
@@ -351,7 +351,7 @@ type gmailBackupCheckpointer struct {
 	pending []string
 }
 
-const gmailCheckpointShardMaxRows = 1000
+const gmailCheckpointShardMaxRows = 250
 
 func newGmailBackupCheckpointer(ctx context.Context, opts gmailBackupOptions, total int) *gmailBackupCheckpointer {
 	enabled := opts.Checkpoints &&