Aspect Ratio Calculator
This aspect ratio calculator does two jobs
This aspect ratio calculator does two jobs
How to use Aspect Ratio Calculator
- Pick a common aspect ratio preset or type your own ratio width and height.
- Enter a new width or height and let the tool fill in the matching dimension.
- Read the simplified ratio and decimal, then copy the final dimensions.
About Aspect Ratio Calculator
This aspect ratio calculator does two jobs. First, it reduces any width and height to its simplest ratio (for example, 1920 x 1080 becomes 16:9) and shows the matching decimal value. Second, it holds a ratio constant so you can solve for a missing dimension: pick a ratio or type your own, enter a width, and the correct height is filled in automatically (and vice versa).
It works with whole pixels or decimal values, so it handles both clean ratios like 3:2 and cinema ratios like 1.85:1 or 2.39:1. The presets cover the sizes people resize for most often, including YouTube (16:9), vertical Reels and TikTok (9:16), square social posts (1:1), and standard photo ratios. There is also a "simplified from px" readout so you can double-check what ratio your final numbers actually represent.
Everything runs entirely in your browser using plain arithmetic. Nothing is uploaded, no image is required, and there is no sign-up. Results are exact math on the numbers you type; keep in mind that when a computed dimension is not a whole number it is rounded to two decimals, so round to the nearest pixel yourself if you need integer sizes.
Frequently asked questions
- How do I find the aspect ratio of my image or video?
- Enter your pixel width and height in the two dimension fields. The tool reduces them to the smallest whole-number ratio (shown as "simplified from px") and also gives the decimal width-divided-by-height value.
- How do I resize while keeping the same aspect ratio?
- Choose a preset or type a ratio (for example 16 and 9), then enter either the new width or the new height. The other dimension is calculated automatically so the proportions stay identical.
- Which aspect ratios does it support?
- Any ratio you type, plus one-click presets for 16:9, 9:16, 4:3, 1:1, 3:2, 21:9, 2:3, 5:4, and cinema ratios 1.85:1 and 2.39:1. Decimal ratios are fully supported.
- Why is my calculated height a decimal instead of a whole pixel?
- Not every width divides evenly into a given ratio, so the exact answer can include a fraction of a pixel. The tool rounds to two decimals; round to the nearest whole number when you need an integer pixel size.
- Is my data uploaded anywhere?
- No. All calculations happen locally in your browser with basic math. Nothing is sent to a server, there are no uploads, and there is no account needed.
- Can I use it for print or canvas sizes, not just pixels?
- Yes. The math is unitless, so you can enter inches, centimeters, or any unit. Just keep both fields in the same unit and the ratio and scaling still work correctly.