Email Attachment Size Limits & How to Make PDFs Fit
Email attachment limits are stricter than they appear. This guide covers common Gmail and Outlook limits, why PDFs fail to send, and the two fastest ways to make files fit.
Attachment limits at a glance
These are the common limits most users run into. Your account or company policy can be lower, so treat this as a baseline.
| Provider | Typical limit | Notes |
|---|---|---|
| Gmail | 25 MB | Google Drive links are used for larger files. |
| Outlook (internet email) | 20 MB | Often lower for corporate servers. |
| Outlook.com | 25 MB | Limit can vary by account. |
Outlook limits vary by account type; 20 MB is a safe target for most internet email accounts.
Why a PDF under the limit can still fail
Email systems encode attachments for transport, which adds overhead. A PDF that is 24 MB on disk can grow beyond 25 MB once encoded, especially if there are multiple attachments or inline images in the same message.
Some servers also apply their own caps that are lower than published limits. That is why a small safety margin matters when you need reliable delivery.
Two ways to make PDFs fit
Use compression when you want one file that fits. The email-ready tool optimizes structure and images first, aiming for the target size without visible changes.
Use splitting when the file is too large to compress without losing quality. The split-by-size tool creates ordered parts under the limit so you can send multiple attachments.
Choosing a safe target size
If Gmail allows 25 MB, a 20-24 MB target is often safer for consistent delivery. For Outlook, 18-20 MB is a good default unless you know the account allows more.
When you see send errors, lower the target by a few megabytes and try again. A smaller target reduces retries and keeps recipients from getting bounced messages.
Size targets vs quality controls
Size targets are best when you must hit a strict limit. Quality controls are useful when the document is image-heavy and you care about clarity.
Smart quality balances both by finding the highest quality that still fits your size limit. It is a good default for scans, contracts, and portfolios.