Aspect Ratio Calculator
Enter a width and height to see the simplified aspect ratio and the nearest common one, or choose a mode to scale to a new width or height without distortion.
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Formula
ratio = (width / g) : (height / g), where g = greatest common divisor
new height = new width x height / width
new width = new height x width / height
The nearest common ratio is the one from this list (and its portrait form) whose width / height is closest: 1:1, 5:4, 4:3, 3:2, 16:10, 16:9, 21:9, 32:9. Width and height must be whole numbers; resized results are rounded to two decimals.
Worked example
1920 x 1080: the greatest common divisor is 120, so the ratio is 1920/120 : 1080/120 = 16:9 (1.7778).
Resize to a width of 1280: height = 1280 x 1080 / 1920 = 720. Resize to a height of 720: width = 720 x 1920 / 1080 = 1280.
Frequently asked questions
How do I find the aspect ratio of an image?
Divide both the width and the height by their greatest common divisor. For 1920 x 1080 the divisor is 120, which gives 16:9.
How do I resize without stretching?
Keep width / height constant. To scale 1920 x 1080 to a width of 1280, the height is 1280 x 1080 / 1920 = 720.
What are the common aspect ratios?
1:1 (square), 5:4, 4:3 (older screens and many photos), 3:2 (35 mm photos), 16:10, 16:9 (HD video and most monitors), 21:9 (ultrawide) and 32:9 (super ultrawide). Portrait video such as 9:16 is the same ratio turned around.
Why does my size not match a common ratio exactly?
Many sizes are rounded for hardware reasons. A 1366 x 768 screen reduces to 683:384 (1.7786), which is within 0.1% of 16:9 (1.7778), so it is sold as 16:9.