Try the calculator
Runs in your browser. No signup, upload or saved inputs.
When this is useful
Use source width and height in pixels. The tool keeps the same shape when calculating the new height, so it cannot turn a landscape interface into a responsive mobile layout.
How to use this calculator
- Enter positive whole-number source dimensions, such as 1920 and 1080. The simplified ratio uses their greatest common divisor.
- Enter a target width to calculate the height that preserves the original shape. Review the exact proportional value before choosing practical export dimensions.
- If the destination requires a different shape, decide whether to frame, crop or record again. Do not stretch the product to make the numbers fit.
Worked calculation
An illustrative 1920 × 1080 source has a 16:9 ratio. At a target width of 1280 pixels, its proportional height is 720 pixels. At a width of 1000, the exact height is 562.5, which needs a deliberate whole-pixel export choice.
Formula and units
Simplified ratio = width ÷ GCD : height ÷ GCD. Proportional height = target width × source height ÷ source width.
Limits and checks
Some encoding workflows require even dimensions. The displayed nearest-even suggestion is a practical rounding aid and may slightly alter the exact ratio. Check the requirements of your chosen encoder and placement.
Your next step
Test a representative frame at the intended display size before approving all scene layouts.
References and scope
Examples are illustrative production guidance, not measured customer results. General workflows are not promises of product compatibility. Read our editorial approach and current Demovela scope.