Aspect Ratio Calculator
Calculate aspect ratios from width and height
Enter Width/Height
Select a preset or enter a custom ratio
Enter either width or height, and the other will be calculated automatically
Calculation Result
What is Aspect Ratio Calculator?
Aspect Ratio Calculator is a tool for checking the aspect ratio of a width and height pair, or calculating dimensions that match a specific ratio. It is useful when working with images, videos, thumbnails, and design assets.
The tool has one mode for calculating a ratio from existing dimensions and another mode for calculating dimensions from a selected ratio. The result is shown both as a simplified ratio like 16:9 and as a decimal value.
How to Use
Calculate an Aspect Ratio
- Open the “Calculate Aspect Ratio” tab.
- Enter the width and height.
- Review the simplified ratio and decimal value.
In this mode, the tool also shows the input dimensions, the greatest common divisor, and the reduction process used to simplify the ratio.
Calculate Dimensions
- Open the “Calculate Dimensions” tab.
- Choose a preset ratio or enter a custom ratio.
- Enter either the width or the height.
- Review the calculated value for the other side.
Once one side is entered, the other side is calculated automatically according to the selected ratio.
Main Features
Simplified Ratio Display
The tool turns values like 1920 × 1080 into a simpler ratio such as 16:9. This makes it easier to recognize what kind of format a size belongs to at a glance.
Decimal Ratio Display
The result is also shown as a decimal value such as 1.78. That is useful when you want to compare ratios numerically or think in terms of CSS aspect-ratio values.
Presets and Custom Ratios
Common ratios can be selected from presets, and custom ratios can also be entered when you need to work with less common formats.
Use Cases
- Checking whether an image or video is
16:9,4:3, or another ratio - Calculating the correct size for thumbnails or social media images
- Verifying whether a design element keeps the intended proportions
- Planning a resize while preserving the original ratio
Things to Keep in Mind
- Ratio checking requires both width and height to be positive numbers
- For dimension calculations, it is easiest to choose the ratio first and then enter one side
- When using a custom ratio, it helps to double-check the width and height ratio values before relying on the result
Input and Output Example
1920 × 1080 → 16:9
For example, if you keep a 16:9 ratio and set the height to 720, the result becomes:
1280 × 720