Drop the PDF and press the button. The tool works in three stages, cheapest first, and stops at the first one that gets the file under 18 MB.
Images are recompressed in place first, so text, links and forms stay exactly as they were. Only when a file still will not fit are the pages rebuilt as images, and even then an invisible text layer keeps the words searchable. A file already under the cap is handed back untouched. If your file is already small enough, you do not need this tool.
Gmail is generous by mail standards and still catches people out, because its limit is measured after base64 encoding adds a third to the file. Eighteen megabytes on disk is about 24.7 MB encoded, safely under. Anything larger triggers the Drive-link fallback, which is convenient for some recipients and a problem for others.
Where the 18 MB limit comes from
- Gmail attachment cap25 MB, measured after encoding
- Safe file size on disk18 MB
- Recipient on Outlook.com20 MB encoded
- Recipient on corporate Exchangeoften 10 MB
- Gmail's own fallback above the capGoogle Drive link
Caps like this are rarely revisited once set. They are written into a portal's upload form at launch, sized for the storage and bandwidth of the day, and outlive both. The practical response is not to argue with the number but to produce a file that clears it while staying readable, which is what the ladder below does.
How the tool hits 18 MB
Add the PDF
Drop it or browse. It is read into browser memory; nothing is uploaded, so a slow connection makes no difference.
Stages one and two: tidy, then the images
Unused objects, thumbnails and stale metadata go first, which costs nothing at all. Then the pictures inside the file are recompressed in place, starting at 200 ppi, while your text, links and form fields are left exactly as they were.
Stage three, only when it is needed
If the images were not where the weight was, the pages are rebuilt as pictures with an invisible text layer behind them, so the words stay searchable. It probes at 150 dpi, works out the resolution that should fit, and will not go below 60 dpi.
Download, and read the result line
It shows the final size and which stage produced it. If none fitted, you still get the smallest attempt, labelled honestly, rather than a file that silently missed the target.
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
The honest answer depends on page count and on what is on the pages. Text pages are cheap because a rendered page of black text compresses extremely well as a JPEG. Colour scans and photographs are expensive because every pixel carries information the encoder has to keep. The estimator uses typical figures to show which attempt your file is likely to land on.
When it cannot reach 18 MB
Some documents will not fit legibly, and the tool says so rather than pretending. When the result line reports a miss, three moves usually solve it:
- Split first. Use Split PDF to break the file into parts and compress each. Most portals accept several attachments even when each one is capped at 18 MB.
- Rescan the source. A fresh 150 dpi greyscale scan compresses far better than a colour scan that has already been through one compressor. Every pass costs quality, and the first pass should start from the cleanest source.
- Check the real limit. Portals sometimes state one number and accept another. Read the fine print, or try a slightly larger file before compressing harder than you need to.
The encoded size is the one that 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
The files people compress for portals are the ones that identify them: passports, ID cards, certificates, bank statements, tax forms. Uploading them to a compression website in order to upload them again to the portal doubles the exposure for no benefit.
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
The questions people have with a 18 MB cap in front of them.
01Why 18 MB and not 25 MB?
Gmail applies its 25 MB limit to the encoded message, and base64 encoding adds about 37 percent. An 18 MB file encodes to about 24.7 MB, safely under. A 20 MB file does not.
02Can I stop Gmail turning my attachment into a Drive link?
Yes: make the file small enough to attach. Under 18 MB on disk, Gmail attaches it as a normal file with no prompt. For larger files, split the document and send two messages.
03Will the text still be readable?
For text documents, yes, and usually at the first attempt. For colour scans and photo-heavy pages, later attempts soften the image visibly. The result line tells you which attempt produced the file, and the estimator above predicts it.
04Will the text still be selectable?
Usually, yes. The first two stages leave the text exactly as it was. If the file only fits by rebuilding the pages as pictures, an invisible text layer goes behind them so the words can still be searched and copied.
05What if the file cannot get under 18 MB?
You still get the smallest attempt, with the result line stating the final size honestly. Split the file into parts, or rescan the source in greyscale at a lower resolution, and try again.
06My file was already small. Why did it grow?
The tool checks the size first and hands a file that already fits straight back, untouched. If the file is already under the cap, send it as it is.
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.