Aspect Ratio Calculator
The Aspect Ratio Calculator works out the missing width or height for any ratio, with presets for video, photo and social media formats such as 16:9, 4:3, 1:1, 9:16 and 1.91:1.
About this tool
The Aspect Ratio Calculator works out the missing width or height for any ratio, with presets for video, photo and social media formats such as 16:9, 4:3, 1:1, 9:16 and 1.91:1.
How to use it
- Choose a preset or enter your own ratio width and height.
- Type a width to get the matching height, or a height to get the width.
- Check the proportional preview box.
Good to know
- 16:9 is the standard for HD video and YouTube, e.g. 1920 × 1080 px.
- 9:16 is the vertical format used by Stories, Reels and TikTok, e.g. 1080 × 1920 px.
- 1.91:1 is the usual Open Graph link-preview ratio, e.g. 1200 × 630 px.
- To keep a ratio, height = width × (ratio height ÷ ratio width).
- In CSS the aspect-ratio property, e.g. aspect-ratio: 16 / 9, keeps an element’s proportions.
Runs entirely in your browser — nothing you enter is uploaded or stored.
Frequently asked questions
How do I calculate aspect ratio?
Divide width by height and reduce the fraction: 1920 × 1080 reduces to 16:9. To find a missing side, multiply the known side by the ratio.
What size is 16:9?
Common 16:9 sizes are 1280 × 720 (HD), 1920 × 1080 (Full HD) and 3840 × 2160 (4K UHD).
What aspect ratio is best for Instagram?
Instagram feed posts support 1:1 square and 4:5 portrait; Stories and Reels use 9:16.
What is the aspect ratio of an OG image?
About 1.91:1, typically 1200 × 630 px, which is what most social networks use for link previews.