About the Aspect Ratio Calculator
Find the aspect ratio of any width × height, or calculate a missing dimension for 16:9, 4:3, 21:9 and custom ratios.
Also known as: aspect ratio, 16:9 calculator, resize dimensions, image aspect ratio, video aspect ratio, screen ratio.
How to use this calculator
- Enter calculate.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
W : H = (W ÷ GCD) : (H ÷ GCD) · H = W × b ÷ a
Worked example
Using the values pre-filled in the calculator above:
- Calculate: Aspect ratio from width & height
- Width = 1,920
- Height = 1,080
the calculator returns:
- Aspect ratio: 16 : 9
- Decimal: 1.7778
- Megapixels: 2.074