Aspect Ratio Calculator
Aspect Ratio Calculator width height ratio finder scale image dimensions screen proportion calculatorFind and preserve width-to-height proportion
Enter original width and height in the same unit. Optionally enter a new width. The tool simplifies the ratio and calculates the matching height without stretching the shape.
What an aspect ratio says
Aspect ratio compares width with height. A 16:9 frame is 16 units wide for every 9 units high, whether those units are pixels, inches, centimeters, or feet. It describes shape rather than physical size or image resolution. Two images can share 16:9 while containing very different pixel counts.
How simplification works
For whole-number dimensions, the calculator divides width and height by their greatest common divisor. Dimensions 1920 and 1080 share a divisor of 120, producing 16:9. Decimal measurements are scaled to integers before simplification when practical. The displayed decimal is width divided by height and provides another quick comparison.
Worked resize example
Start with an image 1920 pixels wide and 1080 pixels high. Its simplified ratio is 16:9. Enter a new width of 1280. Multiplying 1280 by 1080/1920 produces a matching height of 720 pixels. Exporting at 1280 by 720 preserves the original proportions.
Cropping versus stretching
If a destination frame uses another ratio, proportional scaling alone cannot fill it without empty space. You must crop part of the image, add padding, or accept distortion. Stretching width and height independently changes circles into ovals and makes people or products look unnatural. Decide which tradeoff fits the design before resizing.
Assumptions and limits
Width and height must be positive and use the same unit. A calculated pixel height may be fractional; image software normally requires rounding to a whole pixel, which can introduce a tiny ratio difference. The tool does not resize a file, inspect metadata, choose crop placement, estimate print quality, or account for pixel aspect ratios used by some video formats.
Aspect Ratio FAQ
Is 1920×1080 always 16:9?
Yes, when pixels are square, because both dimensions reduce to 16:9.
Does a higher ratio mean higher quality?
No. Ratio describes shape; pixel count, encoding, and source quality affect detail.
Can dimensions use inches?
Yes. Any common unit works because equal units cancel in the comparison.
Related tools
Worked example: a smaller HD frame
A 1920-by-1080 frame reduces to 16:9; scaling its width to 1280 produces a proportional height of 720.