Compress image for Outlook Attachment (20 MB Cap)
Outlook and Microsoft 365 email cap individual attachments at 20 MB.
Your images stay on your device. Nothing is uploaded.
Outlook.com and Microsoft 365 email cap individual message attachments at 20 MB. Exchange-hosted Outlook (corporate email) is often capped much lower — typically 5–10 MB by IT policy.
For corporate Outlook, land photos under 2 MB and check with your IT team on the actual cap. Outlook desktop does not render WebP in-body — use JPEG for image content embedded in the email itself.
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Frequently asked questions
- What's the attachment size limit for Outlook?
- Outlook caps attachments at the size the preset on this page targets. Anything above the cap either gets rejected or gets converted to a link-share fallback (like Gmail's Drive attachment).
- Why compress before attaching to Outlook?
- Recipients may be on slow mobile connections, and their servers may enforce lower caps than yours. Compressing before send maximises deliverability and speeds up download for recipients on mobile.
- Does Outlook compress images automatically?
- Outlook does not re-compress attachments the same way social media platforms do — what you send is what the recipient receives. So the size at send equals the size at receive.
- What format is best for Outlook?
- JPEG is the safest universal choice for email attachments — every email client can preview it inline. WebP support varies (Outlook desktop can't preview WebP), so JPEG remains the default.
- Is my image uploaded to a server?
- No. Compression runs entirely in your browser. Only when you attach the compressed result to your email does it leave your device.
Compress an image for Outlook.
Land under the target size in seconds. Nothing uploaded — runs entirely in your browser.
Start compressing