See the simplified ratio of a width and height, then scale one dimension to another. Pure math in the page.
See the simplified ratio and scale one dimension to another. Pure math in the page.
What the aspect ratio calculator does
Enter a width and height to see the ratio in its simplest form, then enter a new width to get the matching height that keeps the same proportions. Useful for resizing images, video frames and design canvases.
Frequently asked questions
What is a simplified ratio?
The width and height divided by their greatest common divisor, so 1920×1080 becomes 16:9.
Can I scale down by height instead?
Type the desired height into the width box as a starting point, or flip the two inputs; the same math applies.
Is anything uploaded?
No. The maths runs in the page.
How to use it
- Enter the original width in pixels into the first input box and the original height into the second box.
- Read the simplified aspect ratio displayed below the inputs; for example, 1920×1080 reduces to 16:9.
- Type a new width value into the scale-width input box to specify the desired pixel width.
- Read the calculated scaled height shown in the result field; the tool computes it while keeping the original ratio intact.
Where it comes in handy
A photographer has a 6000×4000 JPEG from a mirrorless camera and needs to resize it to 3000 pixels wide for web use. The calculator returns a scaled height of 2000, confirming the output stays at 3:2.
A video editor exports footage at 1920×1080 and must fit it into a 1280-pixel-wide slot on a presentation slide. The tool shows the matching height is 720 pixels, so the project frame can be adjusted without manual division.
A designer prepares a mobile banner at 1080×1920 pixels and wants to scale it up to 2160 wide for a retina display. The scaled height comes out to 3840, giving the exact dimensions for the export.
Worth knowing
- The ratio is found using the greatest common divisor, so not every pair of numbers produces a familiar ratio; 1280×720 simplifies to 16:9, but 1024×768 simplifies to 4:3, and 1280×800 simplifies to 8:5.
- The scaled height calculation divides by the GCD and multiplies, which means remainders are discarded — if the math does not divide evenly you will see a slightly smaller result than exact proportional scaling would give.
- The tool only scales width to height; there is no separate input to start from a target height and solve for width, so you would need to swap the two inputs manually if you want to begin from a desired height value.