Aspect Ratio Calculator
Resize an image, display, or rectangle while preserving its original width-to-height proportion. Choose whether the new width or the new height is known; the calculator solves the other dimension.
How to use the Aspect Ratio Calculator
Enter the known resized dimension, positive whole-number original width and height, and either a positive new width or positive new height.
Review orientation, pixel aspect ratio, crop versus fit behavior, units, and required whole-pixel rounding.
Read simplified aspect ratio, proportional target width, and proportional target height.
Formula
Simplified aspect ratio divides original whole-number width and height by their greatest common divisor. New height = new width × original height ÷ original width; new width = new height × original width ÷ original height.
Example
A 1,920 × 1,080 image simplifies to 16:9; at 1,280 px wide the matching height is 720 px.
Assumptions and limitations
- Pixels or lengths are square and the rectangle is resized without cropping, stretching, rotation, or nonuniform scaling.
- Aspect Ratio Calculator treats the entered values as estimates and does not infer missing project, account, or personal details.
- Calculations retain working precision except where the cited method requires an intermediate rounding step; displayed values are then formatted separately. Source rules and dated rates must be rechecked when they change.
Sources
- OpenStax: College Algebra 2eAlgebraic, ratio, radical, equation, and function formulas. Reviewed 2026-08-14.
- OpenStax: Prealgebra 2eOfficial formula, rate, or program guidance used by this calculator. Reviewed 2026-08-14.
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Frequently asked questions
How does the Aspect Ratio Calculator work?
Simplified aspect ratio divides original whole-number width and height by their greatest common divisor. New height = new width × original height ÷ original width; new width = new height × original width ÷ original height.
What information should I enter in the Aspect Ratio Calculator?
Enter the known resized dimension, positive whole-number original width and height, and either a positive new width or positive new height, then verify orientation, pixel aspect ratio, crop versus fit behavior, units, and required whole-pixel rounding.
What should I verify before using this Aspect Ratio Calculator result?
Pixels or lengths are square and the rectangle is resized without cropping, stretching, rotation, or nonuniform scaling.
Reviewed 2026-08-14 · solve-width-or-height-v2 · content-2026-08-14 · Trusty Calculator Editorial Team