Pre-send check
Before composing the email
Quick lookup before you waste 5 minutes writing the email and attaching — only to have it bounce because the file is 26 MB.
All tools
Email Attachment Size Checker
Check if your file will fit as an email attachment for Gmail, Outlook, iCloud, ProtonMail, and 8 other email providers.
- 100% local
- No signup
- Works offline once loaded
or
What this does
Find out which email providers will accept your file — before you hit send.
Different email providers cap attachments at different sizes: Gmail 25 MB, Outlook web 20 MB, iCloud Mail Drop 5 GB, ProtonMail 25 MB. Drop your file (or enter its size), see at a glance which providers it'll fit through and which will bounce it. No upload — runs locally.
How to check attachment fit
- 1
Drop a file or type a size
Either drag your file (we just read the size, not the contents) or type a size in MB. Both work.
- 2
See compatibility across 11 providers
Sorted by size limit ascending. Each provider shows fits/too-big with its current size cap.
- 3
If too big — try alternatives
Above 25 MB, the tool suggests sending a link via BulkShare / WeTransfer / Smash instead of attaching. One click to our send-large-files guide.
When this saves you time
Multi-recipient
Sending to mixed providers
If recipients are split across Gmail and old Outlook installs, the smallest cap wins. Check both before sending.
Enterprise IT
Knowing internal mail limits
Corporate IT often configures even lower caps (10-50 MB). Knowing the cap saves an awkward back-and-forth with the admin.
Mobile
Phone email apps with their own quirks
Some mobile apps fail silently on attachments their underlying server would accept. Pre-check via web first.
Legacy clients
Old Outlook still common in some industries
Legal, finance, government — old Outlook clients with 20 MB caps are still common. Worth knowing before sending privileged or time-sensitive material.
Email provider attachment caps (May 2026)
Sorted by size. Caps can change without notice — re-check if your file is on the boundary.
Outlook (web) — 20 MB
Best for: Default cap; smaller than Gmail surprisingly often
Gmail / Yahoo / AOL / Proton / Tutanota — 25 MB
Best for: Standard for most consumer email
Enterprise (typical) — 35 MB
Best for: Configured by IT, varies widely (10-50 MB common)
Fastmail — 50 MB
Best for: More generous than most
Outlook (Microsoft 365) — 100 MB
Best for: Higher with OneDrive auto-attach as a link
iCloud Mail Drop — 5 GB
Best for: Only for Apple-to-Apple recipients via iCloud
Email attachment tips
- 01
Email expands the file size by ~33%
Email encoding (MIME/base64) inflates attachments. A 19 MB file becomes ~25 MB on the wire. Stay 5 MB under the cap to be safe.
- 02
Send a link, not an attachment, for anything over 20 MB
Even if it fits the cap, large attachments slow recipient inboxes and risk getting flagged as suspicious. Just send a link.
- 03
ZIP doesn't help much
If your file is a photo/video/PDF (already compressed), ZIPing adds no real size reduction. Send the original, or send a link.
- 04
Corporate IT may scan and strip
Even within the size cap, corporate email gateways often strip executables, ZIPs, and macro-enabled documents. Test with a small ZIP first to know your sandbox.
No signup. No upload. Just the result.
Local only
Files never leave your browser.
Everything runs locally in this tab. Nothing uploads, nothing stores on a server, nothing indexes.
Ready in seconds
Fast — no queues, no ads.
No progress bars stuck at 99%, no rate limits, no 'please wait' screens. Drop, click, done.
On Pro
Branded delivery, when needed.
When the free tool isn't enough, deliver from files.your-agency.com — password and view analytics included.
More free tools for the handoff.
ZIP File Creator
Eliminates manual zipping steps when sending multiple files to clients.
Compression Toolkit
Lets users actually compress files right away instead of guessing output ranges.
Client Delivery Email Generator
Saves time and reduces confusion in client handoffs by standardizing delivery messages.
PDF Compressor
Helps users send oversized PDFs that fail email and portal upload limits.
PDF Merge
Most PDF merge tools upload your sensitive documents to a server. Ours never does — everything happens in your browser with pdf-lib.
PDF Split
Extracting pages from a PDF usually requires uploading to a third party. This tool does it locally in your browser.
Frequently asked
Gmail: 25MB. Outlook (web): 20MB. Outlook (Microsoft 365): 100MB. iCloud Mail Drop: 5GB (Apple recipients only). ProtonMail: 25MB. Yahoo: 25MB. AOL: 25MB. Most enterprise email systems: 10-50MB depending on admin config. The tool checks all of these.
Email was designed in the 1970s for text. Attachments were retrofitted later, and each provider sets its own limit based on infrastructure and abuse concerns. There's no universal standard — which is why this tool is useful.
Use a file transfer service instead of email attachment. BulkShare, WeTransfer, Smash, Filemail all handle files larger than email allows. The tool recommends specific services based on your file size.
Sometimes. ZIP compression helps for text/code (50-80% reduction) but barely helps for already-compressed files (JPG, MP4, PDF). The tool also suggests compression if it would bring your file under the threshold.
Usually yes for the same provider. But cross-provider: Gmail's 25MB applies to OUTGOING attachments. If you receive a 30MB attachment forwarded through your Gmail, it depends on the original sender's limits too.