Aspect Ratio Calculator
When a platform asks for a 16:9 or 4:5 asset, you need the second dimension. Enter the original size and the new width, height or percentage, and the calculator returns the matching value plus the simplified ratio.
Key facts
- Category
- Image Utilities
- Price
- Free
- Account
- Not required
- Processing
- In your browser
- Input
- Local files or pasted data
- Platform
- Modern desktop and mobile browsers
What it does
When a platform asks for a 16:9 or 4:5 asset, you need the second dimension. Enter the original size and the new width, height or percentage, and the calculator returns the matching value plus the simplified ratio.
Resize dimensions while preserving the ratio, with presets for common formats.
How to use it
Here is the short version of using Aspect Ratio Calculator.
- Enter the original size — Width and height in pixels.
- Choose how to scale — Set a new width, a new height or a percentage.
- Read the result — The simplified ratio and megapixel count update as you type.
Features that matter
What Aspect Ratio Calculator does well.
- Nothing leaves your device — The work happens in your browser tab. There is no upload endpoint in this app, so your files and text cannot be stored, logged or seen by us.
- No upload wait — You skip the round trip to a server entirely. Results are limited by your own CPU, not by network speed or queue size.
- Free, no account, no quotas — No sign-up wall, no watermark, no daily limit. Optional accounts only exist to save favourites and presets across devices.
Frequently asked questions
Is my dimensions safe to use here?
Yes. This tool runs entirely in your browser using JavaScript. Nothing you paste or open is sent to a server, and the page keeps no copy after you close it.
Do I need to create an account?
No. Every tool is fully usable without signing in. An account only adds saved favourites and reusable presets.
Does it work on a phone?
Yes. The interface is mobile-first with large touch targets and a stacked layout, so it works on phones and tablets as well as desktops.
How do I calculate a 16:9 height?
Divide the width by 16 and multiply by 9. For a 1920px width that gives 1080px. The calculator does this automatically.
Does the calculator apply the size to a file?
No. It only calculates dimensions. Use the Resize Image tool to apply them to an actual image.
Open Aspect Ratio Calculator
Try it now — it runs in your browser and needs no account.
Open the tool