How aspect ratio is calculated
Aspect ratio is width compared with height. To get the simplest form, divide both by their greatest common divisor. To resize without stretching, keep the ratio the same.
Example: 1920 × 1080 has a GCD of 120, so the ratio is 1920 ÷ 120 : 1080 ÷ 120 = 16:9. Resizing it to 1280 wide gives 1280 × 1080 ÷ 1920 = 720 high: 1280 × 720.
Sizes for each platform
| Where | Ratio | Recommended size |
|---|---|---|
| YouTube video | 16:9 | 1920 × 1080 (1080p), 3840 × 2160 (4K) |
| YouTube Shorts, TikTok, Reels, Stories | 9:16 | 1080 × 1920 |
| Instagram feed, portrait | 4:5 | 1080 × 1350 |
| Instagram feed, square | 1:1 | 1080 × 1080 |
| YouTube thumbnail | 16:9 | 1280 × 720 |
| Twitch and Kick stream | 16:9 | 1920 × 1080 or 1280 × 720 |
Common 16:9 resolutions
640 × 360, 854 × 480, 1280 × 720 (720p), 1920 × 1080 (1080p), 2560 × 1440 (1440p), 3840 × 2160 (4K), 7680 × 4320 (8K).
Picking stream settings? The stream settings finder matches resolution to your upload speed, and the video file size calculator shows how big a recording will be.
Frequently asked questions
What aspect ratio is 1920 × 1080?
16:9. Divide both by 120.
What size is 9:16 for TikTok and Shorts?
1080 × 1920 pixels. That's 16:9 turned on its side.
What ratio is 2560 × 1080?
Exactly 64:27, about 2.37:1. Monitors at that size are sold as "21:9" ultrawide, which is a rounded marketing name.
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