The moment this actually comes up is rarely abstract. You are attaching a PDF to an email or uploading it to an application form, and it gets rejected, too big, try again. The frustrating part is that the limit is never the same twice: your email provider has one number, the job portal has another, and the government form you filled out last month had a third. Here is what those limits actually tend to be, and what to do about each one.
What email providers actually allow
Gmail caps attachments at 25MB, and that is a combined limit across everything in the message, not per file. Outlook and Office 365 vary by plan but commonly sit at 20MB to 25MB as well. Those numbers sound generous until you remember that a single scanned page can run a megabyte or more, so a 10-page scanned contract can quietly approach that ceiling on its own, especially if it went through a phone camera rather than a proper scanner.
If you are close to the limit, running the file through our compress tool on the Recommended preset usually solves it without any visible change to the document. You do not need to chase the smallest possible file for an email attachment, you just need to clear the number.
Job applications and portals: usually the tightest limit
This is where things get stricter. A lot of applicant tracking systems, the software companies use to collect résumés and cover letters, cap uploads at 5MB, and some go as low as 2MB or 1MB. A résumé alone is rarely the problem here, since a text-based one-page document is a few hundred kilobytes at most. The usual culprit is a portfolio PDF with embedded images, or a scanned reference letter added to the same file.
If a single document is over the limit and it is mostly text with one or two images, Recommended compression will typically clear a 5MB or 2MB cap easily. If you are closer to a 1MB limit and the file has several images in it, Extreme is usually the right starting point rather than something to try only if Recommended is not enough.
Government and visa forms: the tightest of all
These are the forms that ask for 1MB, 500KB, or even 200KB, and they are almost always asking for a single scanned document, a passport page, a utility bill, a signed form. There is very little room to work with at these sizes, so Extreme compression is the starting point, not a last resort. If the document still will not clear the limit after that, the underlying scan resolution is usually the actual problem: a document scanned or photographed at very high resolution has more to compress out than one captured at a reasonable setting in the first place.
If one pass is not enough
Compressing a file twice in a row rarely helps much, most of what a compressor can safely remove is already gone after the first pass, so a second run on the same file usually saves almost nothing. If you are still over the limit after compressing once at the appropriate level, the more effective move is usually to address the source: retake a phone photo of a document with better lighting instead of a dim, high-noise shot that has more to compress out, or scan at a lower resolution in the first place if your scanner defaults to something excessive for a document that is just going to be read on a screen. This piece goes into more depth on what compression actually changes under the hood, which helps explain why a second pass does not just keep shrinking the file indefinitely.
A quick reference
- Email attachment (Gmail, Outlook): 20 to 25MB. Recommended compression almost always clears this.
- Job application portal: commonly 5MB, sometimes 1 to 2MB. Recommended usually works; use Extreme if you are near the low end.
- Government or visa form: often 500KB to 1MB, sometimes 200KB. Start with Extreme rather than working up to it.
- If a single document will not shrink enough on its own, check whether it needs to be one file at all. Splitting a multi-page scan into the pages that are actually required sometimes solves the limit faster than compressing everything harder.
None of these limits are arbitrary cruelty, they exist because these systems are handling enormous volumes of uploads and every megabyte costs someone storage and bandwidth. Knowing the number you are actually working against before you start saves a round of trial and error, compress, check the size, compress again.