Aspect Ratio Calculator

How Aspect Ratio Calculator works

Enter an original size and a new width or height — the other side is calculated to preserve the ratio. Everything happens inside this page: the tool reads your input, runs the calculation or conversion locally, and hands the result back to you. Nothing is transmitted, because there is no backend to transmit it to.

That design choice is deliberate. Most free tool sites upload your files to a server, process them there, and quietly keep a copy. Toolcin cannot do that — the site is a set of static files. If your connection dropped the moment the page finished loading, every tool would still work.

Two ways in: preset or free

Pick a preset — 16:9, 9:16, 4:3, 3:2, 1:1, 21:9 or 4:5 — and the ratio is locked. Choose Free and the ratio is derived from the width and height you enter, which is what you want when matching an existing image.

Either way, giving a new width returns the height that keeps the shape. A 1920 × 1080 frame at 1280 wide becomes 720 tall; the arithmetic is width × (h/w).

Which ratio for which platform

The numbers below are the ones that get asked for, and they matter because every platform crops rather than letterboxes a mismatched upload.

Cropping is not scaling

Resizing a 16:9 video into 9:16 without changing the ratio either adds black bars or cuts the sides. Filling the frame means losing content, and the tool cannot tell you what is safe to lose.

For an existing image, crop to the target ratio first and then scale — that order preserves sharpness and avoids the two-step resampling that softens detail.

Good to know

• Works offline once loaded, including on flights and in locked-down networks.
• No file size limit beyond your device's own memory.
• Free to use, with no account and no usage counter.
• Results are produced locally, so they are not logged or shared with anyone.

Questions