Aspect Ratio Calculator
Work out matching dimensions for any ratio and export a blank canvas at that size.
Get The Other Number Right
Aspect ratio problems are always the same problem: one dimension is fixed and the other has to match. A thumbnail must be 16:9 at 640 pixels wide, a banner has to fill an ultrawide header, a video export needs to be vertical without letterboxing.
Type either dimension and the other follows. The simplified ratio, the decimal, the megapixel count and the nearest standard sizes are all shown at once, and a blank canvas at the exact size can be downloaded as a template.
Key features
- Works in both directions — set the width or the height and the other follows the ratio.
- Eight presets — from square through widescreen to 2.39:1 anamorphic.
- Simplifies the real ratio — 1920×1080 reads as 16:9, not as 1.778:1.
- Standard sizes at your ratio — 4K down to 360p, which is usually the question behind the question.
- Downloadable blank canvas — a real PNG at the exact pixel size, optionally labelled.
This tool runs entirely inside your browser using native Web APIs. Your files and text are never uploaded to a server, never logged and never shared with third parties.
How to use: Aspect Ratio Calculator
- Pick a ratio
Use a preset or type your own ratio values. - Enter one dimension
Type a width or a height; the other is calculated immediately. - Read the standard sizes
The common heights at your ratio are listed with their usual names. - Download the canvas
A blank PNG at that exact size, useful as a template or placeholder.
Technical specifications
| Processing location | Entirely in your browser — no server round trip |
|---|---|
| Data uploaded | None. Files and text never leave your device |
| Price | Free — no account, no trial, no usage cap |
| Category | Calculators |
| Works offline | Yes, once the page has loaded |
| Browser support | Chrome 90+, Edge 90+, Firefox 90+, Safari 15+ |
| Interface languages | English, 中文, हिन्दी, Español, العربية |
Frequently asked questions
What is the difference between 16:9 and 1.778:1?
Nothing — they are the same ratio written differently. Broadcast and computing conventionally use whole-number pairs like 16:9; cinema uses a decimal against 1, like 2.39:1. This tool shows both so you can use whichever the software in front of you expects.
Why is my calculated dimension not a whole number?
It is rounded, because pixels are whole. Some ratios do not divide evenly into common widths — 21:9 at 1920 wide gives 822.86, shown as 823. If exactness matters, choose a width divisible by the ratio's width value.
Does the ratio matter more than the resolution?
For fitting a space, yes. A platform that expects 16:9 will letterbox or crop anything else regardless of how many pixels it has. Get the ratio right first, then pick a resolution high enough for the display.
What is the blank canvas for?
Three common uses: a placeholder while a real asset is produced, a template to design against at the correct size, and a quick check that an upload form accepts the dimensions before you spend time rendering the real thing.