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Best Image Format for Email Attachments

You're trying to email some photos. Simple enough, except: which format works? Will the recipient be able to open them? Will the email even send if the files are too big?

The short answer: JPG. It's compatible with everything, keeps file sizes reasonable, and looks good for photos.

Why JPG Is the Safe Choice

  • Universal support. Every email client, every device, every operating system can open a JPG. You literally cannot find a computer that won't display it.
  • Good compression. JPG files are smaller than PNG, which matters when email servers limit attachment sizes.
  • Great for photos. JPG was designed for photographs. The compression works well with natural images, skin tones, and landscapes.

Format-by-Format Breakdown

JPG

Best for: Photos, anything where file size matters.
Downsides: Doesn't support transparency. Slight quality loss from compression (usually not noticeable).

PNG

Best for: Screenshots, images with text, graphics with transparency.
Downsides: Much larger files than JPG. A 5MB PNG might be 500KB as a JPG.

HEIC

Best for: iPhone storage—not email.
Downsides: Many recipients won't be able to open it. Windows requires a special extension, older Macs won't recognize it, and some email clients won't display the preview. Convert to JPG before emailing. Convert HEIC to JPG here.

WebP

Best for: Websites.
Downsides: Email client support is inconsistent. Some will display it fine, others will show a broken image or force the recipient to download and open it separately. Not worth the risk.

PDF

Best for: Documents, multi-page layouts, printable files.
If you're sending a single photo, PDF is overkill. But if you want the recipient to print something exactly as you designed it, PDF preserves the layout.

Email Attachment Size Limits

Most email providers limit attachment sizes:

  • Gmail: 25 MB total
  • Outlook: 20 MB
  • Yahoo: 25 MB
  • iCloud: 20 MB (but Mail Drop handles larger files via iCloud links)

If you're hitting these limits, you have two options: compress your images more (lower JPG quality) or use a file sharing service like Google Drive or Dropbox instead of attachments.

Compressing Photos for Email

A photo straight from a modern phone camera is often 3-8 MB. That's fine for one or two photos, but try attaching 10 and you'll hit the limit.

Tips for smaller files:

  • Lower the quality slightly. JPG at 80% quality looks nearly identical to 100% but is significantly smaller.
  • Resize if appropriate. A 4000×3000 pixel photo is overkill if the recipient just needs to see what you're talking about. Resize to 1600×1200 and the file drops dramatically.
  • Don't use PNG for photos. PNG is lossless, which means huge files. Convert to JPG for email.

Sending iPhone Photos

If you're emailing directly from an iPhone, iOS usually converts HEIC to JPG automatically for non-Apple recipients. But if you're downloading photos to a computer first, they'll stay as HEIC and you'll need to convert them.

The safest workflow: convert to JPG before attaching. Quick HEIC to JPG conversion.

Summary

  • Photos: JPG
  • Screenshots with text: PNG (or JPG if file size is an issue)
  • Graphics with transparency: PNG
  • Documents: PDF
  • HEIC, WebP, AVIF: Convert to JPG first

When in doubt, JPG. It's been the universal standard for 30 years and will work for another 30.