For email, the winner is almost always JPG — with PNG as the exception for logos, screenshots, and anything needing transparency. That's the whole recommendation. The reason comes down to two things email cares about more than the web does: universal compatibility and total message size.
Why JPG wins for email
Email clients are a zoo. People read messages in Outlook, Gmail, Apple Mail, decade-old corporate software, and phones you've never heard of. JPG is the one raster format every single one of them displays without complaint. It also compresses photos small, which keeps your message under the size caps mail servers enforce.
Those caps are real and stricter than people expect:
| Service | Typical attachment limit |
|---|---|
| Gmail | 25 MB |
| Outlook / Microsoft 365 | 20 MB |
| Yahoo Mail | 25 MB |
| Many corporate servers | 10 MB or less |
And that's the ceiling. In practice, a message full of huge images is slow to send, slow to receive, and sometimes silently bounced. A few well-compressed JPGs keep everything moving.
When to use PNG instead
Reach for PNG when the image is:
- A screenshot with text — JPG smears lettering; PNG keeps it sharp.
- A logo or icon with flat colors or a transparent background.
- A diagram or chart with hard edges.
PNG files of photos are large, so don't use it for photographs. But for crisp graphics, PNG looks better and often compresses smaller than a JPG of the same graphic.
What to avoid
- WebP and AVIF in email. They're great on the web, but some email clients still won't render them inline or in a preview. Don't make your recipient guess. Stick to JPG/PNG for anything going through email.
- Uncompressed originals straight from a phone or camera. A modern phone photo can be 5–12 MB. Three of those blow past a corporate limit instantly.
- Embedding dozens of full-size images inline. If you have many, zip them or share a link.
Shrink before you send
Two quick steps handle almost every oversized email:
1. Resize the dimensions. A photo doesn't need to be 6000 pixels wide to be viewed in an email. Scaling it down to 1600–2000 px on the long edge cuts the file size dramatically and still looks sharp on any screen.
2. Compress. After resizing, run it through compression to squeeze out the rest. For JPG, quality around 80% is invisible to the eye but much lighter on the wire.
You can do both in your browser without uploading anything. The Image Compressor reduces file size (and never outputs something bigger than the original), while the Image Converter switches formats — say a heavy PNG photo into a lean JPG. Both run on Canvas locally, need no account, and work offline after the first visit, so private attachments never leave your device.
The rule of thumb
Photo going in an email? JPG, around 80% quality, no wider than ~2000 px. Screenshot, logo, or diagram? PNG. Keep the whole message comfortably under your recipient's limit — aim for a few MB, not tens — and it'll arrive fast and display everywhere. Save WebP and AVIF for your website, where they belong.