Aspect Ratio Calculator
Enter a width or height, and this calculator gives you the matching dimension for any aspect ratio — so images and videos resize without stretching. The presets cover the ratios you meet constantly: 16:9 video, 4:3 classic displays, 1:1 social posts, 21:9 ultrawide, 9:16 vertical video.
It also detects the ratio from dimensions you type (say, 1920×1080) and simplifies it (16:9), which is handy when you need to describe a source file or check whether two images share proportions.
How to use
- Choose a preset ratio, or type your own ratio like 3:2.
- Enter the width to get the height, or the height to get the width.
- Or type both dimensions to detect and simplify the ratio you already have.
Frequently asked questions
What aspect ratio is 1920×1080?
16:9. Both numbers divide by 120: 1920÷120 = 16 and 1080÷120 = 9. This is the standard HD video and monitor ratio.
How do I keep aspect ratio when resizing?
Scale both dimensions by the same factor. To halve the width of a 16:9 image, halve the height too — this calculator computes the exact partner dimension for any input.
What ratio is vertical video (TikTok/Reels/Shorts)?
9:16 — the vertical flip of widescreen. Record at 1080×1920 for full-quality vertical video on all major platforms.
Why does my photo look stretched?
Its width-to-height proportion was changed during resize. If an image is displayed at a different ratio than its native one, circles become ovals and faces widen — lock the ratio to fix it.