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Type a width and a height to see the aspect ratio, or pick a preset such as 9:16 and type one side to get the other. It runs in your browser and nothing is uploaded.
- Pick a preset and change either side, and the other side follows.
- Typing both sides shows the simplified ratio, such as 1920 × 1080 is 16:9.
- Everything is worked out in your browser, so no file or number leaves your device.
Calculate an aspect ratio#
Whole pixels only. The result rounds to the nearest pixel.
How to use it#
- Pick a preset, or choose Custom and type your own width and height.
- Change the width or the height. With the ratio locked, the other side updates.
- Untick the lock to read the ratio of any two numbers.
Common aspect ratios and where they are used#
| Ratio | Shape | Typical use |
|---|---|---|
| 16:9 | Landscape | YouTube videos and thumbnails (1280 × 720) |
| 9:16 | Vertical, full screen | Reels, YouTube Shorts and vertical video pins (1080 × 1920 at full HD) |
| 2:3 | Tall | Pinterest image pins (1000 × 1500) |
| 4:5 | Portrait | Portrait feed posts |
| 1:1 | Square | Square posts and profile pictures |
Exact limits change, so check the platform's own page for the current figures. Our guides link to them: YouTube thumbnail size, YouTube Shorts size, Instagram Reel size and Pinterest pin size.
How the maths works#
An aspect ratio is width divided by height, written in its simplest whole numbers. To simplify, divide both sides by their greatest common divisor. For 1920 × 1080 that number is 120, which gives 16 and 9. To find a missing side at a fixed ratio, multiply or divide: for a 9:16 video that is 1080 wide, the height is 1080 × 16 ÷ 9 = 1920.
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Frequently asked questions
How do I calculate an aspect ratio?
Divide the width and the height by their greatest common divisor. For 1920 × 1080 you get 16:9. The calculator above does this as you type.
What is the aspect ratio for Reels and Shorts?
Both use 9:16 vertical for full screen. At full HD width that is 1080 × 1920 pixels.
What aspect ratio is a YouTube thumbnail?
16:9, and 1280 × 720 pixels is the recommended size.
How do I find the height for a given width?
Pick the ratio, keep the lock on and type the width. The height is worked out for you.
Is my image or number sent anywhere?
No. The calculator runs in your browser and sends nothing.
Keep reading
YouTube Thumbnail Size: 1280 × 720 and Every Spec That Matters
The YouTube thumbnail size is 1280 × 720 at 16:9. See the file types, size limits and daily cap, and why a saved thumbnail may be smaller.