How to Compress Images for Email
Shrink photos to a few hundred KB so they send fast and land in the inbox — not the spam folder.
Email clients are terrible at handling large images. Gmail caps attachments at 25MB, Outlook at 20MB, and plenty of corporate servers reject anything over 10MB. Even when a big attachment does go through, it's slow to send and annoying to receive.
The good news: a phone photo is 4–8MB, but a perfectly good email photo only needs to be 300–800KB. Here's how to bridge that gap in under a minute.
Know your limits
Before compressing, know your target. Gmail allows 25MB per message (including encoding overhead, so stay under ~20MB of actual files). Outlook caps at 20MB. Many corporate and government servers reject messages over 10MB.
A safe target: keep each image under 1MB, and total attachments under 10MB. For sharing a batch of photos, that means roughly 10–20 images at 300–800KB each — far below the limit with room to spare.
Resize first — email doesn't need 12MP
A 4000×3000 phone photo is 12 megapixels, but on screen it'll be viewed at maybe 800×600. Resizing to 1280×960 (or even 1600×1200 for a large monitor) preserves full on-screen quality while cutting file size by 75%+.
This single step usually takes a 5MB photo down to ~1MB before any compression.
Convert and compress
If you're emailing photos, JPEG at 70–85% quality is the practical choice — universally openable and small. If the recipient is tech-savvy and you want even smaller files, WebP at 75% is a good option.
For screenshots and documents, PNG is fine but large; converting to JPEG or WebP will dramatically shrink them. Compress at 70–80% quality — for email, slight quality loss is completely acceptable and usually invisible.
Strip the EXIF metadata too. You don't need to send your GPS coordinates with every photo.
Batch it and send a ZIP
Sharing 20 vacation photos? Don't attach 20 separate files — compress them all at once and download a single ZIP archive. One file is easier to send, easier to download, and (bonus) ZIP adds its own compression on top.
With a browser-based tool like CompressFast, this is a single drag-and-drop: up to 30 images in, one ZIP out, all processed locally without uploading your photos anywhere.
Start compressing your images
Free, 100% local, no upload. Drop up to 30 images at once and get results in seconds.
FAQ
How do I make an image small enough to email?
Resize to 1280–1600px on the longest edge, convert to JPEG, compress at 70–85% quality, and strip metadata. A 5MB phone photo becomes ~500KB — well under any email limit.
What is the Gmail attachment size limit?
25MB per message, but that includes encoding overhead, so aim to keep actual files under ~20MB. For larger files, Gmail will automatically offer to send via Google Drive instead.
Should I compress photos before sending by email?
Almost always yes. It's faster to send, faster to receive, less likely to bounce, and the recipient can't tell the difference at screen resolution. The only exception is when the recipient needs the full-resolution original for printing or editing.
How do I compress a batch of photos for email?
Drag them all into a browser compressor (up to 30 at once with CompressFast), set resize + JPEG + 80% quality, and download a single ZIP. Then attach the one ZIP file to your email.
Is WebP OK to send by email?
Technically yes, but not every recipient's viewer opens WebP natively (some older Outlook versions don't). For maximum compatibility, JPEG is the safer email format. WebP is better reserved for the web.