Aspect Ratio Calculator
Calculate a matching image width or height from the original dimensions. Get a proportional result and a rounded pixel value for your next resize.
- Solve a missing dimension
- Choose width or height
- See rounded pixel guidance
Enter the original shape
Use the original width and height, such as 1920 by 1080. These values define the proportion to preserve.
Set the dimension you know
Choose width and enter 1280. The corresponding height is 720, preserving the original 16:9 shape.
Account for rounding
Some proportions produce fractional pixels. The exact value and nearest whole pixel are both shown so you can judge the rounding.
Apply dimensions elsewhere
This calculator changes no files. Transfer the computed dimensions to an image resizer or video editor and keep its ratio lock enabled where possible.
Aspect Ratio Calculator FAQs
Larger dimensions alone cannot create detail missing from the source; this tool only computes geometry.
Select height as the known dimension. The result multiplies that height by the original width-to-height ratio.