Why is a 24 MB file rejected by a 25 MB limit?

Attachments are base64-encoded, which adds about a third to their size. 24 MB on disk is 32 MB in the message.

Only for text, spreadsheets and uncompressed files. Photos, PDFs with images and videos are already compressed; a ZIP of them is the same size.

Will the recipient see a difference?

At the "email" setting, text stays sharp and photos look the same on a screen. Keep the original if the file is going to print at large size.

Email attachment size limits, and how to get under them

Updated October 29, 2026

Every mail service caps attachments, and the cap is smaller than it looks: a file that is 25 MB on disk becomes about 34 MB once it is encoded for email. That is why a "24 MB" video bounces on a "25 MB" limit.

This page lists the real limits of the big providers and the fastest way to get a PDF, a photo or a video under them without installing anything.

The limits, provider by provider

Gmail: 25 MB per message, all attachments together. Anything larger is turned into a Google Drive link automatically, which the recipient must click and which can expire if you move the file.

Outlook.com and Microsoft 365: 20 MB per message on the web, 10 MB per attachment on many corporate Exchange servers (admins often set it lower). Yahoo Mail: 25 MB. iCloud Mail: 20 MB, or Mail Drop links up to 5 GB when sent from Apple Mail.

Because of the encoding overhead (about 33 percent), aim for 18 MB on a 25 MB service and 14 MB on a 20 MB service. Below those figures the message always goes through, whatever the recipient's server does.

Shrink a PDF

Most heavy PDFs are heavy because of images: scans at 300 dpi, photos pasted at full size, or a logo embedded on every page. Compressing re-samples those images to what a screen or a printer actually needs and leaves the text untouched.

Drop the file on the compress PDF tool, pick "email" quality and download. A 40 MB scanned contract usually comes out between 3 and 8 MB, still readable and printable. If one file is still too big, split it into chapters and send two messages.

Shrink photos

A phone photo is 3 to 8 MB and 4000 pixels wide. Nobody needs that in an email: 1600 pixels wide at 80 percent JPEG quality looks identical on a screen and weighs 300 to 500 KB. Ten photos then fit in one message with room to spare.

The compress image tool does both steps at once (resize to a maximum side, then re-encode) and keeps the EXIF data if you ask it to. It also accepts HEIC straight from an iPhone.

Shrink a video

Video is the one that never fits: a minute of 4K from a phone is 300 MB. Re-encoding it at 720p and "low" quality brings it to 10 to 20 MB per minute, fine for a clip of the kids or a screen recording.

If it is still too large, send a short part of it as a GIF, or share a link instead: for video, a link to a cloud folder is simply the right tool.

Tips

Compress before attaching, not after the bounce: the bounce can take an hour to arrive.
Several small attachments are better than one big one: the recipient can open each on a phone.
If the recipient is on a corporate server, assume 10 MB.
Everything on this site runs in your browser: the contract or the photos never leave your computer.

Questions

Why is a 24 MB file rejected by a 25 MB limit?: Attachments are base64-encoded, which adds about a third to their size. 24 MB on disk is 32 MB in the message.
Does zipping help?: Only for text, spreadsheets and uncompressed files. Photos, PDFs with images and videos are already compressed; a ZIP of them is the same size.
Will the recipient see a difference?: At the "email" setting, text stays sharp and photos look the same on a screen. Keep the original if the file is going to print at large size.