Enter integer pixel dimensions to reduce their width-to-height ratio. Then choose a new width to derive a proportional height. This assumes square pixels. Anamorphic media can have a different display aspect ratio from its stored frame dimensions.
How the calculation works
The exact ratio divides width and height by their greatest common divisor. Desired height = desired width × original height ÷ original width. The tool also shows a nearest-even height for workflows that need even dimensions; rounding can slightly alter the aspect ratio.
Worked example
A 1920 × 1080 frame reduces to 16:9. At a width of 1080 pixels, its proportional height is 607.5 pixels. A nearest-even option is 608 pixels. That is a landscape frame; making a 1080 × 1920 portrait frame requires cropping, padding or reframing rather than simply keeping the original ratio.
Before using the result
Check the export preset’s accepted dimensions and pixel aspect ratio. A fractional result is geometry, not a valid fractional pixel dimension in an exported frame. Choose practical dimensions deliberately and compare the final framing. Avoid stretching faces or graphics just to fill a target ratio.
Keep the source values with your project notes. A number calculated from an assumed bitrate or representative sample is only as useful as that assumption. Check a real file or measured export when a deadline, upload cap or storage purchase depends on the answer.