Gmail counts its 25 MB sending limit before encoding. A receiving server may count after encoding, which adds about 37 percent, so 18 MB is the size that fits a 25 MB cap on both sides. That is the number this page aims at.
The tool works down in three stages and stops at the first that fits. Under the target the file sends as a normal attachment rather than being turned into a Drive link.
Gmail is generous by mail standards and still catches people out, because the file is not the only size that counts. Google's sending limits page says the 25 MB is counted before encoding, but base64 encoding then adds about 37 percent, and the server at the other end may check that larger figure. Eighteen megabytes on disk is about 24.7 MB encoded, under 25 MB either way. Above 25 MB, Gmail offers a Drive link instead, which is convenient for some recipients and a problem for others.
Where the 18 MB limit comes from
- Gmail sending limit25 MB, counted before encoding
- Safe file size on disk18 MB
- Sending from the Outlook app20 MB per message
- Recipient on Exchange Server10 MB by default, after encoding
- Gmail's own fallback above the capGoogle Drive link
Google counts the 25 MB sending limit before encoding and its 50 MB receiving limit after it. The working target is lower because the server receiving your message is not always Gmail.
How the tool hits 18 MB
Add the PDF
Gmail allows 25 MB, counted before encoding. Encoding adds about 37 percent, and 18 MB is the largest whole number of megabytes that stays under 25 MB after it. That is the number this page aims at.
The free clean, then images against 18 MB
Structure goes first at no cost. The images then step down from 200 ppi with 18 MB as the target, so the attachment still fits a 25 MB cap after encoding, with room for the message around it.
Stage three, and what it means for a Drive link
If a rebuild is needed the document is a long scan. It is worth knowing that Gmail will offer a Drive link rather than refuse the message, so a near miss is not the failure it appears to be.
Download, and read the result line
It reports the file size before encoding. Under 18 MB, the attachment sends as a normal file and fits a 25 MB cap even where the encoded size is counted.
Structure, then the images in place, then the pages as pictures. It stops at the first stage that fits.
Untouched at the first two stages. If the pages do get rebuilt, an invisible text layer keeps them searchable.
The IDs, forms and statements people compress for portals never leave the device.
What fits in 18 MB, and what does not
Comfortably more than most documents need. Gmail is unusual in that exceeding the limit changes how the message sends rather than whether it sends, so a near miss is not a failure.
When it cannot reach 18 MB
Gmail rarely refuses a message outright, so a miss here changes how it sends rather than whether it sends. Three points:
- Let the Drive link happen. Over the limit, Gmail offers to upload the file and send a link instead. The recipient still gets the document, at full quality, and nothing is lost but the attachment icon.
- Check the server at the other end. Gmail will send up to its own limit, but the receiving system applies its own. A default Exchange Server stops at 10 MB, counted after encoding.
- Split where an attachment is required. Some workflows reject links on principle. Where that is the case, Split PDF and send the parts as separate attachments.
Where the encoded size counts
What the Drive-link fallback changes
When an attachment is too large, Gmail offers to upload it to Google Drive and send a link instead. It works, and it changes the experience for the person on the other end.
- They see a link, not a file. Some recipients, and some spam filters, treat an unexpected Drive link as suspicious. Recruiters in particular are trained to.
- The file lives in your Drive. Delete it, or let the account lapse, and the link breaks. An attachment in their inbox is theirs.
- Corporate gateways may strip the preview or block Drive entirely from outside the organisation.
- It counts against your Drive quota for as long as it exists.
Where people use the 18 MB target
- Client deliverables as real attachmentsmixed
- Applications where recruiters distrust Drive linkstext, fits
- Legal correspondence with the packet attachedtext and scans
- Recipients whose IT blocks external Drive accessany
Why this runs in your browser
Compressing in the browser keeps the document between you and the recipient. Nothing is uploaded until you choose to send it.
The tool is right above
Everything on this page runs in your browser. Scroll up, drop the file, and keep it on your machine.
Common questions
Questions that come up when sending a large file through Gmail.
01Why 18 MB and not 25 MB?
Gmail counts its 25 MB sending limit before encoding, so Gmail itself would send a 20 MB file. Base64 encoding then adds about 37 percent, and a receiving server may count the encoded size against its own 25 MB cap. An 18 MB file encodes to about 24.7 MB and fits either way; a 20 MB file becomes about 27.4 MB and may not.
02Can I stop Gmail turning my attachment into a Drive link?
Yes: keep the file under 25 MB and Gmail attaches it as a normal file with no prompt. Under 18 MB it also fits a 25 MB cap at a server that counts encoded size. For larger files, split the document and send two messages.
03Will the text still be readable?
Yes. Reaching 18 MB costs very little, usually no more than the first rung of the ladder.
04Will the text still be selectable?
Yes, in nearly every case. Gmail attachments at this size do not need the pages rebuilt.
05What if the file cannot get under 18 MB?
You get the smallest attempt with its size, though Gmail will offer a Drive link rather than refuse the message outright.
06My file was already small. Why did it grow?
It hands an already-small file straight back, and under 18 MB it will send as a normal attachment.
07Are my files uploaded anywhere?
No. Rendering and compression run in your browser. The file never leaves the device.
08Is it free?
Free. Every tool, unlimited use, no signup.