📐 Aspect Ratio Calculator
Enter your original width and height, plus an optional new width or height, to find the simplified aspect ratio and scale your dimensions proportionally.
What This Calculator Does
An aspect ratio describes the proportional relationship between an image or screen’s width and height, commonly written as two numbers such as 16:9 or 4:3. This tool simplifies your width and height down to their smallest whole-number ratio and can also scale a dimension proportionally.
How the Math Works
The simplified ratio is found using the greatest common divisor (GCD) of the width and height — both values are divided by their GCD to reach the smallest equivalent whole numbers. To scale proportionally, the tool multiplies your entered new width or height by the original width-to-height ratio to find the matching dimension that keeps the same shape.
Common Uses
- Resizing photos or videos without distorting them.
- Figuring out what resolution matches a standard ratio like 16:9, 4:3, or 21:9.
- Enter either a new width or a new height (not both) to scale proportionally — if both are left at 0, the original dimensions are shown.