About this tool
When sizing an image or video, it's common to ask: if the width is 800px, what should the height be? This tool calculates the simplified ratio (like 16:9) and the decimal ratio the moment you enter a width and height.
It also works the other way: keeping the original ratio fixed, enter a new width or height and the other dimension is calculated automatically. Handy for resizing banners and thumbnails, or picking a video resolution.
Common ratios like 16:9, 4:3 and 1:1 are available as one-click presets. Everything runs in your browser — nothing you enter is sent to a server.
How to use it
- Enter a width and height under Original size, or pick a preset.
- The simplified ratio (e.g. 16:9) and decimal ratio are calculated automatically.
- Under Calculate a size, enter a new width or height and the other value is calculated automatically, keeping the original ratio.
- Use the copy buttons to copy the ratio or the calculated result.
Features
Simplified and decimal ratio
Reduces values like 1920x1080 to a simplified ratio like 16:9, and also shows the decimal ratio (1.778).
Resize while keeping the ratio
Enter a new width or height and the other dimension is calculated automatically, keeping the original ratio.
Common ratio presets
Pick common aspect ratios like 16:9, 4:3 and 1:1 with a single click.
Swap width and height
Swap the width and height values with one click — useful when switching between portrait and landscape.
Frequently asked questions
Can I enter decimal values?
Yes. Both width and height accept decimals; the simplified ratio is calculated using up to 4 decimal places internally.
Can I use this for video resolutions?
Yes. Enter a resolution like 1920x1080 to get its ratio (16:9), and calculate another resolution (like 1280x720) that keeps the same ratio.
Is anything I enter sent to a server?
No. All calculations run in JavaScript in your browser; nothing is sent anywhere.
What happens if width or height is 0 or empty?
The ratio can't be calculated from a value of 0 or less, or an empty field, so no result is shown. Enter a positive number.