Aspect Ratio Calculator
Keep proportions right when resizing images, videos, embeds or screens. Enter an original size or pick a common ratio, then type a new width or a new height and the calculator works out the other one. It also reduces any size to its simplest ratio, such as 1920 × 1080 to 16:9, and names the closest standard ratio.
Calculate Aspect Ratio and Size
Result
Shape preview
How to Use the Aspect Ratio
- Enter the original width and height, or choose a common ratio.
- Type either the new width or the new height; leave the other empty.
- Read the missing dimension, the simplified ratio and the decimal ratio.
- Choose whole pixels or decimals for the rounding.
About This Tool
Video editors, web developers sizing embeds and images, photographers preparing prints, and anyone comparing screen sizes.
Input: Width and height · Output: Ratio and dimensions.
Features and Limitations
Features
- Calculates a missing width or height from either value.
- Simplifies sizes to whole-number ratios with the greatest common divisor.
- Names the nearest standard ratio and the difference from it.
- Twelve presets and a proportional shape preview.
Limitations
- Ratios of non-integer sizes are simplified after rounding to two decimals.
- When both new values are filled in, the tool reports how far that size is from the original ratio instead of changing them.
- Results are computed in your browser; nothing you enter is sent to a server.
Example
1920 × 1080 simplifies to 16:9 (1.7778). At 16:9 a width of 1280 needs a height of 720, and a height of 1350 needs a width of 2400.
Frequently Asked Questions
How do I calculate a height from a width?
Multiply the new width by the original height and divide by the original width: 1280 × 1080 ÷ 1920 = 720.
Why is 1366 × 768 not exactly 16:9?
It simplifies to 683:384, which is 1.7786, very close to 16:9 (1.7778). Many screens use sizes that are only approximately standard.
What is the difference between 16:9 and 1.78:1?
They are the same ratio written differently: 16 divided by 9 equals 1.78.
Can I use it for print sizes in inches or centimetres?
Yes. The maths is unit-free, so enter any unit as long as both values use the same one.
Related Tools
More like this: all Design Helpers tools, all Image & Design tools or the TinySandy home page.