How to Compress Images for Email Attachments

By Gaurav Bhowmick·May 5, 2026·5 min read

Modern phone cameras produce images that are 4-8MB each. Attach three or four of those to an email and you have already hit Gmail's 25MB limit. Here is how to compress your images so they send quickly and open fast for the recipient.

Email attachment limits you need to know

Provider	Max attachment	Note
Gmail	25 MB	Total across all attachments
Outlook.com	20 MB	Per email
Yahoo Mail	25 MB	Per email
Apple iCloud Mail	20 MB	Uses Mail Drop for larger files
Zoho Mail	20 MB	Free plan; higher on paid

These limits are for total attachment size, not per file. If you are sending 5 photos, each needs to be under 4-5MB to stay within the limit. But just staying under the limit is not enough — you also want the recipient to be able to download them quickly.

Target sizes for email images

The attachment limit is the ceiling, but your target should be much lower. A 5MB image and a 300KB image look identical on a phone screen. The smaller one just downloads 15x faster.

Single photo to share: 300-500KB. Looks great on any screen.
Multiple photos (5-10): 150-300KB each. Keeps total under 3MB.
Documents or receipts: 100-200KB. Text is still readable at this size.
Quick reference images: Under 100KB. Fast to open on any connection.

How to compress with MiniPx

Step 1. Open the JPEG compressor on MiniPx. If you need a specific target, use compress to 200KB instead.

Step 2. Upload your photo. MiniPx shows the original size and the compressed size instantly.

Step 3. Adjust the quality slider. For email, 75-80% quality is the sweet spot — visually identical to the original, but 70-80% smaller in file size.

Step 4. Set max width to 1600px. No one is viewing email attachments on a 4K monitor at full resolution. This single change can cut file size in half.

Step 5. Download and attach to your email. Repeat for each image.

Slow connections: why size matters even more

If you are sending photos to someone on a mobile data connection — common in India, Southeast Asia, and parts of Africa — large attachments can take minutes to download. On a 2G connection, a 5MB image takes over two minutes. The same image at 300KB downloads in about 8 seconds.

This is also relevant for recipients who pay per megabyte of data. Sending 20MB of uncompressed photos to someone on a metered plan is inconsiderate. Compress first, and everyone has a better experience.

iPhone HEIC files and email

If you use an iPhone, your camera probably saves photos in HEIC format. Most email clients handle HEIC fine now, but some older systems and Windows machines cannot open them. If you are unsure, convert your HEIC files to JPEG before attaching them.

This conversion also reduces file size. HEIC files from iPhone cameras are typically 2-4MB. Converting to JPEG and compressing to 80% quality brings them down to 200-400KB with no visible quality loss.

Frequently asked questions

What is the maximum email attachment size for Gmail?

Gmail allows attachments up to 25MB total per email. This is the combined size of all attachments, not per file. If you attach 5 images, their total size must be under 25MB. For larger files, Gmail automatically offers to share via Google Drive instead.

What is the attachment limit for Outlook?

Outlook.com (Hotmail) allows up to 20MB per email. Microsoft 365 business accounts may have higher limits set by the IT administrator, but 20MB is the standard. Yahoo Mail allows 25MB, similar to Gmail.

What size should each image be for email?

Aim for 200-500KB per image. This keeps total attachment size manageable when sending multiple photos, and ensures recipients on slow connections can download them quickly. For images that will only be viewed on screen (not printed), this quality level is more than sufficient.

How do I compress multiple images for email at once?

In MiniPx, you can compress images one at a time with your preferred settings. Process each image, download it, then attach all the compressed versions to your email. Each image stays on your device throughout the process — nothing is uploaded to any server.

Will compressing images make them look bad in email?

Not if you use sensible settings. JPEG at 75-80% quality looks excellent on screens. Most email recipients view attachments on their phone or a standard monitor — they will not notice the difference between the original 5MB file and a 300KB compressed version.

More from the blog

How to Compress Images for Email (Under 1MB) →Compress Images for Faster Websites →JPEG vs PNG: When to Use Each Format →

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