Aspect Ratio Resolution Calculator
Resize without distortion — enter an aspect ratio and one dimension, get the pixel value for the other, exactly proportional.
How it works
height = width × ratioH ÷ ratioW (or width = height × ratioW ÷ ratioH)
Keeping an image proportional means holding the ratio of width to height constant. Fix one dimension and the other follows directly: multiply by the ratio’s far term and divide by its near term. This is how you resize to a target width without squashing the picture, or find the matching height for a chosen aspect ratio like 16:9, 4:3 or 21:9. Rounding to whole pixels can nudge the ratio by a hair, which is normal.
Worked example
For 16:9 at 1920 px wide: height = 1920 × 9 ÷ 16 = 1080 px — the familiar 1920×1080. Switch to a 2560 px width and the height becomes 2560 × 9 ÷ 16 = 1440 px.
Frequently asked questions
What is the most common video aspect ratio?
16:9 is the standard for TVs, monitors, YouTube and most phones in landscape. Cinema uses wider ratios like 2.39:1, older content is 4:3, and vertical social video is 9:16 — just the 16:9 numbers swapped.
Why does my resized image look slightly stretched?
Almost always because width and height were changed by different percentages, breaking the ratio. Locking the aspect ratio — or using this tool to compute the matching dimension — keeps it proportional.
Do the pixel results need to be whole numbers?
Screens can only show whole pixels, so the height is rounded to the nearest integer. That can shift the true ratio by a fraction of a percent, which is invisible in practice.
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This calculator is for educational purposes. Double-check important results before acting on them.