Email attachment size limits, and how to get under them
The limits for the main email services, and the quickest way to shrink each kind of file.
You attach a file, press send, and get a bounce: the message is too large. Every email service has an attachment limit, and it is lower than most people expect, especially once the file has been encoded for sending.
The limits
| Service | Approximate limit per message |
|---|---|
| Gmail | 25 MB to send; larger files become Google Drive links |
| Outlook.com and Microsoft 365 | About 20 to 25 MB depending on setup; larger files become OneDrive links |
| Yahoo Mail | 25 MB |
| Apple iCloud Mail | 20 MB, with Mail Drop for larger files |
| Company mail servers | Often 10 MB, set by your IT team |
The one that matters is the smallest limit along the way. You can send 25 MB from Gmail, but if the recipient's company server accepts only 10 MB, the message bounces. For files going to businesses, aim under 10 MB.
Why a 20 MB file will not fit in a 25 MB limit
Attachments are converted to text for sending, using an encoding called Base64, which makes them about 33 percent larger. A 20 MB file becomes roughly 27 MB in transit and fails a 25 MB limit. As a rule of thumb, keep attachments to about 75 percent of the stated limit.
Shrinking each kind of file
PDFs
PDFs made from scans or photos are usually huge because each page is a full-resolution image. The PDF compressor re-renders the pages at a sensible resolution and commonly cuts scan-based PDFs by 80 percent or more. PDFs that are mostly text are already small; if one is large, it probably has embedded photos.
Photos
Phone photos are 3 to 5 MB each. For email, nobody needs more than 2000 pixels across. The image compressor with a max width of 2000 and quality 80 usually brings a photo under 500 KB, so ten photos fit easily.
Videos
A minute of phone video can be 100 MB or more. The video compressor can bring a short clip down to email size by lowering the resolution to 720p and the bitrate. For anything longer than a couple of minutes, a share link is the better option.
Lots of small files
Bundling files into one ZIP with the ZIP tool makes them easier to send and download. It saves real space on documents and spreadsheets, though not on photos, videos and PDFs, which are already compressed.
When to use a link instead
For anything over about 25 MB, or files you need to update after sending, use a cloud share link: Google Drive, OneDrive, Dropbox or iCloud. Links also avoid filling up the recipient's inbox, which some people appreciate more than the attachment itself.
Keeping it private
Many online compressors upload your file to their server. For contracts, payslips and ID documents, compress in the browser instead: every tool on this page processes files on your own device.