Aspect Ratio & Resolution Calculator
Solve missing width/height for a target aspect ratio, and get megapixels and the simplified ratio.
Lock the aspect ratio when resizing to avoid stretching. Enter the original dimensions plus ONE new dimension and the other is solved to keep the ratio. 1920×1080 is 16:9; 2560 wide at 16:9 is 1440 tall. Megapixels = width × height ÷ 1,000,000.
Formula
About Aspect Ratio & Resolution Calculator
Resizing an image, video frame or render target without distorting it means preserving the aspect ratio — and that's a quick division most people redo constantly. This calculator solves the missing dimension: enter the original width and height plus one new dimension, and it computes the other to keep the exact ratio, along with the megapixel count and the simplified ratio. Whether you're matching 16:9, fitting a thumbnail, choosing a render resolution, or planning a responsive layout, it removes the stretching errors that come from guessing the second dimension.
How to use Aspect Ratio & Resolution Calculator
- 1Enter your values into Aspect Ratio & Resolution Calculator — sensible, domain-typical defaults are pre-filled so you see a real result immediately.
- 2The result recomputes live using the formula shown on the page; there is no button to press.
- 3Adjust any input to compare scenarios, then read the worked example to see the substituted numbers.
Why use Aspect Ratio & Resolution Calculator?
- ✓Computes Aspect Ratio & Resolution instantly in your browser — no sign-up, no upload, no server round-trip.
- ✓100% free and unlimited, with the exact formula shown: aspect ratio = W : H.
- ✓Runs entirely client-side, so every value you enter stays private on your device.
- ✓Live recompute as you type, with a worked example and authoritative references for trust.
Frequently asked questions
How do I resize without stretching?+
Keep the width-to-height ratio constant. If you change the width, the new height must be width ÷ aspect ratio (and vice versa). This tool does exactly that — fix one new dimension and it solves the other. Stretching happens when you set both dimensions independently to a ratio different from the original.
What's the aspect ratio of common resolutions?+
1920×1080, 2560×1440 and 3840×2160 are all 16:9 (widescreen/HD/4K). 1920×1200 and 2560×1600 are 16:10. 1080×1080 is 1:1 (square, social). 1080×1920 is 9:16 (vertical/stories). Cinema uses 2.39:1. Matching your output to the target platform's ratio avoids letterboxing or cropping.
How are megapixels calculated and why do they matter?+
Megapixels = width × height ÷ 1,000,000 — total pixel count. They drive memory (an RGBA texture is width×height×4 bytes), render cost, file size and detail. Doubling each dimension quadruples megapixels and memory, which is why 4K is 4× the pixels of 1080p despite being '2× the resolution' per side.
Should I round the solved dimension?+
Yes — pixels are integers, so this tool rounds. Note that rounding can introduce a sub-pixel ratio drift; for pixel-perfect work (video codecs often require even or multiple-of-8 dimensions), pick source and target sizes that divide cleanly. For most images, the rounded result is visually identical to the exact ratio.
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