Image Aspect Ratio Detector
Drop an image and see its pixel dimensions, simplified aspect ratio, decimal ratio, megapixels, orientation, file size, and the closest common preset.
Everything runs in your browser — the file never leaves your device.
How to use
- Drop an image or click to pick one.
- Read the ratio in its simplest form, the decimal version (handy for CSS
aspect-ratio: 1.778 / 1), and the megapixel count. - Compare to the closest preset to know if you're effectively on 16:9, 4:3, etc.
About this tool
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Drop an image and read its pixel dimensions, its simplified ratio, the decimal ratio, megapixels, orientation, file size and the closest common preset. The preset match is the answer to the question you usually have: whether the picture will crop when it goes into a 16:9 slide, a 4:5 social post or a 3:2 print, and which edge will lose. Megapixels answer the other one — how large it can be printed or how much room there is to crop in before the result softens. The dimensions come from decoding the file rather than from its name, so a picture that was resized by someone else reports what it actually is. Nothing is uploaded: the image is decoded in the page and dropped when you clear it.
Frequently asked questions
Why does my 4032×3024 phone photo come out as 4:3?
4032 ÷ 1008 and 3024 ÷ 1008 both equal a small integer (4 and 3 respectively) — the GCD is 1008. That's standard for 12 MP phone sensors, which are physically 4:3 chips.
What does "closest preset" mean?
We score the image against a handful of named ratios (1:1, 4:3, 16:9, 21:9, 9:16, …) and pick whichever is nearest in absolute ratio difference. The percentage tells you how close — under 1% means it's effectively that preset; 5% means you're between two named ratios.
Does it run on huge images?
Yes — the browser decodes the image to read dimensions and then discards the decoded pixels. Even 50 MP files measure instantly. Only metadata stays in memory.
Which ratio should I crop to for a given platform?
Whatever the platform actually renders, which is rarely what it accepts. A feed that displays square thumbnails will centre-crop a 16:9 photo, so composing for the ratio you will be shown in matters more than uploading at the maximum size. Where one image has to serve several surfaces, keep the subject inside the region that survives the tightest crop.
Is a simplified ratio like 3:2 exact?
Only when the dimensions divide cleanly. Many real images are a pixel or two away from a round ratio because of a crop or a resize, so the reduced form shown is the nearest simple description rather than a promise. If you are matching a spec exactly, compare the pixel dimensions themselves — a 1920x1081 image is not 16:9, however close it reads.
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