CSS property · data last changed 10 Nov 2026
aspect-ratio in email clients
Works in 5 of 21. Not supported in Gmail, Gmail Android, Gmail iOS and 13 more.
Your reader in Outlook Classic sees the email without aspect-ratio, even if it looks right where you tested it.
caniemail (MIT) via @emailens/engine 0.18.22
What to do instead in Outlook Classic
Set explicit width and height attributes on <img> elements so blocked or slow-loading images still reserve their space. Use aspect-ratio as a progressive enhancement on container <div>s where it can avoid layout shift in modern clients.
There is no drop-in fix for aspect-ratio in Outlook Classic. Design so the email still reads without it.
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aspect-ratio is not among the 24 features we have screenshotted on real installs. The ones we have →
All 21 clients, problems first
| Client | Support |
|---|---|
| Gmail | Not supported |
| Gmail Android | Not supported |
| Gmail iOS | Not supported |
| Outlook 365 | Not supported |
| Outlook (New) | Not supported |
| Outlook Classic | Not supported |
| Outlook iOS | Not supported |
| Outlook Android | Not supported |
| Outlook for Mac | Not supported |
| Yahoo Mail | Not supported |
| Yahoo Mail Android | Not supported |
| Yahoo Mail iOS | Not supported |
| Samsung Mail | Not supported |
| Thunderbird | Not supported |
| AOL Mail | Not supported |
| Fastmail | Not supported |
Works in 5: Apple Mail, Apple Mail iOS, HEY Mail and 2 more. Show all
| Client | Support |
|---|---|
| Apple Mail | Works |
| Apple Mail iOS | Works |
| HEY Mail | Works |
| Proton Mail | Works See caveat 1 |
| Superhuman | Works |
Caveats (1)
- 1. Proton Mail: Requires iOS 15.
Caveats as recorded by caniemail (MIT), one entry per wording.
How aspect-ratio behaves
aspect-ratio locks an element's height to a fraction of its width, preserving ratio across breakpoints. In email, support is recent and uneven: modern Apple Mail and webmail clients honor it, while Outlook and many mobile clients ignore it. Pre-computed width/height attributes remain the most reliable approach.
- Outlook Classic ignores aspect-ratio entirely.
- Gmail honors aspect-ratio in modern Chromium versions but Gmail mobile apps lag behind.
- Apple Mail respects aspect-ratio reliably across recent macOS and iOS releases.
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fix
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