Key takeaways
- A ratio is the width and height divided by their greatest common divisor: 16:9 for 1920 × 1080, with a decimal ratio of 1.7778.
- Platforms in our registry list these preferred shapes: 9:16, 9:16 or 1:1, 16:9 or 9:16, 16:9 or 1:1, 1:1 or 4:5.
- Rounding to an even number matters because H.264 with common chroma subsampling needs even width and height.
Reading a ratio
Two sizes have the same aspect ratio when their width divided by height gives the same number. 1920 × 1080 and 1280 × 720 are both 16:9, so scaling one to the other never needs a crop.
To change a size without changing the shape, fix one side and let the other follow. The even-number rounding in the last result is for video encoders, which need even sizes.
Common sizes and their ratios
| Size | Simplified ratio | Decimal ratio | Orientation | Height at |
|---|---|---|---|---|
| 1920 × 1080 | 16:9 | 1.7778 | landscape | 608 px |
| 1080 × 1920 | 9:16 | 0.5625 | portrait | 1920 px |
| 1080 × 1080 | 1:1 | 1.0000 | square | 1080 px |
| 1080 × 1350 | 4:5 | 0.8000 | portrait | 1350 px |
| 1440 × 1080 | 4:3 | 1.3333 | landscape | 810 px |
| 3440 × 1440 | 43:18 | 2.3889 | landscape | 452 px |
| 2560 × 1080 | 64:27 | 2.3704 | landscape | 456 px |
Which platforms prefer which ratio
From the platform registry (preferred export shape, not the only accepted one):
| Platform | Preferred ratio | Export size |
|---|---|---|
| TikTok | 9:16 | 1080 × 1920 |
| Instagram Reels | 9:16 | 1080 × 1920 |
| YouTube Shorts | 9:16 or 1:1 | 1080 × 1920 |
| 16:9 or 9:16 | 1920 × 1080 | |
| 9:16 | 1080 × 1920 | |
| X (Twitter) | 16:9 or 1:1 | 1920 × 1080 |
| Facebook Reels | 9:16 | 1080 × 1920 |
| Snapchat Spotlight | 9:16 | 1080 × 1920 |
| Threads | 9:16 or 1:1 | 1080 × 1920 |
| Instagram Feed | 1:1 or 4:5 | 1080 × 1350 |