Free tool # Email attachment size checker:will my file fit? Pick a file or type its size to see which inboxes will take it once email encoding is counted. Only the size is read, in your browser; the file is never opened or uploaded. Updated Oct 23, 2026 Check a file on your device Only the file size is read, in your browser. The file is never opened or uploaded. or Type a size 22 MB file, about 30 MB once email encodes it (Base64). - Gmail (25 MB limit) Too big. Swaps the file for a Google Drive link. Files up to about 18 MB fit. Does not fit - Outlook.com (25 MB limit) Too big. Offers a OneDrive link instead. Files up to about 18 MB fit. Does not fit - Yahoo Mail (25 MB limit) Too big. Refuses the attachment. Files up to about 18 MB fit. Does not fit - iCloud Mail (20 MB limit) Too big. Mail Drop takes over, as a link that expires in 30 days. Files up to about 15 MB fit. Does not fit - Proton Mail (free) (25 MB limit) Too big. Refuses the attachment. Files up to about 18 MB fit. Does not fit - Typical work or school server (10 MB limit) Too big. Bounces, often hours later, sometimes never. Files up to about 7.3 MB fit. Does not fit Too big for some inboxes? Send a link instead. Upload it once and paste the link into your email. A free Link in Seconds file can be up to 250 MB, and every provider accepts a link. See [how to send large files by email](https://linkinseconds.com/send-large-files-via-email) or [what to do when Gmail says the file is too large](https://linkinseconds.com/blog/gmail-file-too-large). [Get a link for your file](https://linkinseconds.com/) Free: every feature, 50 links, up to 250 MB · [Pro: unlimited links, bigger uploads](https://linkinseconds.com/pricing) Most providers cap a message at 25 MB, but that limit applies after Base64 encoding, which makes a file about 37% bigger. So the largest file you can really attach is about 18 MB on Gmail, Outlook.com, Yahoo and Proton free, about 15 MB on iCloud Mail, and about 7.3 MB on a strict 10 MB work server. 1 Drag in your PDF From your desktop or phone, any file works 1 / 4 creating your link… proposal.pdf 2.1 MB Drop to upload proposal.pdf2.1 MB appendix.pdf0.9 MB cover-letter.pdf0.3 MB Resume PDF Your link was just opened First view · 2 min after you sent it New 1 PDF · 2.1 MBOpens in the browser Opened·first view 2 min after sending By the numbers 2,600+ people sharing files 5,100+ links shared 17,400+ times opened Most providers cap a message at 25 MB, but that limit applies after Base64 encoding, which makes a file about 37% bigger. So the largest file you can really attach is about 18 MB on Gmail, Outlook.com, Yahoo and Proton free, about 15 MB on iCloud Mail, and about 7.3 MB on a strict 10 MB work server. ## How to check an attachment - 1 ### Pick the file or type its size Choose the file from your device, or type its size in KB, MB or GB. Picking a file only reads its size; the contents stay on your device. - 2 ### Read the verdict for each inbox Each provider shows whether the encoded file fits its limit, and the largest file it would take. Check the recipient's side too: their server may be stricter than yours. - 3 ### Too big? Send a link instead Upload the file once and paste the link into your email. The message stays tiny, so it never bounces, and the recipient opens the file in their browser. ## Why Base64 makes attachments bigger Email was built for text, so attachments are converted to Base64: every 3 bytes of your file become 4 text characters. That alone adds 33%. The encoded text is then broken into lines of 76 characters, each ending in a line break, and the message carries headers on top. Together that is about 37%, which is why this checker compares the encoded size, not the size on your disk, with each provider's limit. ## Both ends have a limit Your provider's limit is only half of it. The recipient's mail server has its own, and corporate and university servers are often stricter than consumer inboxes, commonly 10 MB. A message that leaves Gmail fine can still bounce at the other end, sometimes hours later, sometimes silently. When you do not know the recipient's setup, plan for the 10 MB row. ## Send it as a link instead A link is a few bytes of text, so it fits every inbox. Upload the file, copy the link, paste it into your email. On Link in Seconds a free file can be up to 250 MB, and you can add a password or an expiry date and see when it was opened. Step by step guides: [send large files via email](https://linkinseconds.com/send-large-files-via-email) and [what to do when Gmail says the file is too large](https://linkinseconds.com/blog/gmail-file-too-large). The full provider table, with what each one does when you go over, is in [email attachment size limits](https://linkinseconds.com/blog/email-attachment-size-limits). ## What this checker does with your file Nothing beyond asking your browser for its size. The page uses the browser's File API to read the size of the file you pick; it never reads the contents, never uploads anything, and keeps no record. You can switch off your internet connection after the page loads and it still works. ## Frequently asked questions Still stuck? [Ask us directly](https://linkinseconds.com/contact) and a real person answers. Email sends attachments as Base64 text, which adds about a third to the size, plus line breaks and headers. A 22 MB file becomes roughly 30 MB in transit, over the 25 MB limit. About 18 MB on a 25 MB provider (Gmail, Outlook.com, Yahoo, Proton free), about 15 MB on iCloud Mail and about 7.3 MB on a typical 10 MB work or school server. No. When you pick a file, your browser only reports its size. The contents are never read, and nothing is sent to a server. You can also just type a size. Upload it and paste a link into the email instead. A link fits every inbox. On Link in Seconds a free file can be up to 250 MB; for anything bigger, use a transfer service or a cloud drive link. ## Keep reading [Which way should you send this file? A 30-second decision guideOne flowchart for every kind of send](https://linkinseconds.com/blog/which-way-to-send-a-file)[Every app's file size limit in 2026, and the second limit each one hidesThe advertised number, and the real one](https://linkinseconds.com/blog/file-size-limits-by-app)[How to send a file without uploading it anywhereDevice to device, nothing stored, no size cap](https://linkinseconds.com/blog/send-files-without-uploading-them) ## Every link feature is free. Pro adds room and website hosting. [Compare every plan →](https://linkinseconds.com/pricing) Free $0 free forever 50 links · 500 MB total · every link feature - Password, expiry & view limits - Advanced analytics + notify-on-open - Custom name, your domain, no branding - Links never expire, nothing goes offline [Start free](https://linkinseconds.com/signup) Pro · Monthly $9/mo billed $9 every month Unlimited links · 15 GB · 500 MB per file - Everything in Free, every link feature - Host up to 10 websites from a .zip - Links keep working if you cancel - Cancel anytime [Go Pro](https://linkinseconds.com/pricing) Most popular Lifetime $149$99 once one payment, no renewals Unlimited links · 30 GB · pay once, keep it - Website hosting, with the most storage and sites - One payment, no subscription - Best value for steady client work - 30 GB storage, 500 MB per file [Buy Lifetime](https://linkinseconds.com/pricing) Pro · Yearly $4.08/mo billed $49/yr Unlimited links · 15 GB · billed once a year - Save 55% vs paying monthly - Everything in Free, every link feature - Host up to 10 websites from a .zip - Links keep working if you cancel - Cancel anytime [Go Pro](https://linkinseconds.com/pricing) Coming from WeTransfer, DocSend or tiiny.host? [See the comparisons →](https://linkinseconds.com/wetransfer-alternative) ## Your link is 10 seconds away Sign in free with Google (one tap, no form) and share one clean, trackable link. [Get started free](https://linkinseconds.com/signup) ## Explore more [Upload time calculator](https://linkinseconds.com/upload-time-calculator)[Send large files via email](https://linkinseconds.com/send-large-files-via-email)[Gmail file too large](https://linkinseconds.com/blog/gmail-file-too-large)[Email attachment size limits](https://linkinseconds.com/blog/email-attachment-size-limits)[Compress a PDF](https://linkinseconds.com/compress-pdf) Source: https://linkinseconds.com/email-attachment-checker