Yes — and the limit that hurts most isn't from your ESP, it's from Gmail clipping at 102 KB of HTML. Beyond that, Gmail truncates the body and hides your unsubscribe link, killing engagement.
Pro tip: The 102 KB rule applies to the raw HTML, not images. Images load separately and don't count toward clipping.
The numbers that matter
| Limit | Source | Recommendation |
|---|---|---|
| 102 KB HTML | Gmail clipping | Stay under 100 KB |
| 1-2 MB total | Mobile load time | Compress every image |
| 200 KB / image | Render speed | Use WebP or compressed JPG |
| 600 px width | Mobile inbox | Single column on mobile |
How to stay under 100 KB of HTML
- Trim inline CSS — keep only what you need.
- Avoid HTML comments and tracking-script blobs in the body.
- Don't paste from Word — it inflates the markup.
- Reuse modular blocks instead of copy-pasting variants.
Image weight: 5 quick wins
- Resize before upload — never use 4 MB camera files.
- Compress with TinyPNG or Squoosh.
- Prefer JPG for photos, PNG only for transparency, WebP if supported.
- Use background colours instead of background images where possible.
- Add descriptive alt text — it helps when images don't load.
Build lightweight newsletters fast — try Mailpro free
Mailpro's drag-and-drop builder warns you when HTML exceeds 100 KB and includes a built-in image editor and compressor. Build a newsletter · Image editor
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