You write a quick email, attach a few weekend photos, hit send — and it bounces. Or worse, it silently never arrives. The cause is almost always attachment size. Here's how email size limits actually work, and how to shrink images so your emails land the first time.
Prep photos for email: drop them into the compressor, set a per-image target of 200 KB, and attach the smaller files.
Compress before sendingThe limits (they're tighter than you think)
Email systems encode attachments with a ~33% overhead (Base64), so the practical limit is lower than the advertised one:
| Provider | Nominal limit | Safe practical total for attachments |
|---|---|---|
| Gmail | 25 MB | ~18 MB of actual files |
| Outlook / Microsoft 365 | 20–34 MB (varies) | ~10–15 MB |
| Many corporate servers | 10 MB | ~5–7 MB |
| Older receiving mail servers | 5–10 MB | often less |
The binding constraint is frequently the receiving server, which you can't see or control. Conservative practice: keep total attachments under 10 MB, and under 5 MB when emailing businesses or institutions.
How much to compress per photo
Email recipients view photos on screens — phones and laptops. A screen-appropriate photo does not need camera resolution:
- Casual sharing: target 200–500 KB per photo, or cap dimensions at 1920 px. Ten photos then total 2–5 MB, safely deliverable.
- Quick previews: 100 KB per photo keeps a 20-photo album under 2 MB.
- Screenshots and documents: PNG input converts well to WebP at 150–250 KB.
At these sizes, photos still look excellent on a phone screen. Recipients who want full-resolution originals can get them via a cloud link on request.
Steps
- Open the JpegDiet compressor and drop in all the photos you plan to attach.
- Set a target size per image (200 KB is a good default) or cap dimensions at 1920 px.
- Choose JPG for photos or WebP for mixed content.
- Download all results and attach the compressed versions instead of the originals.
- Sanity-check the total attachment size in the compose window before sending.
When compression isn't the right tool
If the recipient genuinely needs originals — a print shop, a client buying photos, an archive — don't degrade them for email. Upload the full-resolution files to a cloud drive and send a sharing link instead. Compression is for the 95% of cases where the images are meant to be looked at, not reprocessed.
One more reason it matters
Bloated attachments don't just risk bounces — they fill recipients' mailboxes (a real cost on mobile data), and they slow sync on every device that receives the message. Small emails are simply better netizens.