UtilityBaseCalculators
Aspect Ratio Calculator
Solve missing dimensions for 16:9, 4:3, and any custom aspect ratio.
Updated February 8, 2026
How to use the aspect ratio calculator
- 1Choose a preset ratio or enter a custom one.
- 2Type the dimension you know — the other is calculated instantly.
- 3Or switch to reverse mode to simplify a width × height into a ratio.
Common uses
- Size video embeds and thumbnails correctly.
- Resize images without stretching.
- Find the ratio of an existing image or screen.
Frequently asked questions
What height matches a 1280-pixel width at 16:9?
Height = width × 9 ÷ 16, so 1280 × 9 ÷ 16 = 720 pixels. Enter the ratio and width and the tool computes it instantly.
How do I find the aspect ratio of an image I already have?
Use reverse mode: enter the width and height, and the tool simplifies them to the smallest whole-number ratio (e.g., 1920×1080 → 16:9).
What ratio should vertical videos use?
9:16 is the standard for Reels, Shorts, and TikTok — typically 1080×1920 pixels.
Why do my resized images look stretched?
The new dimensions don't match the original ratio. Compute the missing dimension with this calculator (or use an aspect-locked resizer) so proportions stay identical.
About this tool
The aspect ratio calculator solves the missing side of a proportion: give it a ratio (like 16:9) and one dimension, and it computes the other. Presets cover the ratios you meet daily — 16:9 video, 4:3, 1:1 squares, 9:16 vertical video, 21:9 ultrawide, and 3:2 photography — or enter any custom ratio. It also works in reverse: enter a width and height to find their simplified ratio. Essential for resizing video embeds, cropping thumbnails, and scaling images without distortion.
Like everything on UtilityBase, the aspect ratio calculator runs entirely in your browser — nothing you enter is uploaded or stored on a server. It's free to use with no account required. Browse more calculators here.
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