Gaming
Screen Resolution & Aspect Ratio Calculator
Analyze display resolutions, calculate lowest-term aspect ratios via GCD, and scale dimensions.
Aspect Ratio, Scaling, and the Numbers Behind Them
The ratio shown is the exact one — computed with the greatest common divisor, so 3440×1440 honestly reads 43:18 rather than the marketing approximation "21:9". The exact ratio matters when letterboxing video or matching overlays: a 43:18 canvas is not the same rectangle as 2.333…, and subtle stretching shows up at the edges first.
Scaling between resolutions keeps the ratio only if you multiply both dimensions by the same factor. Going 1080p → 1440p uses the factor 1.3333, which is why 1920×1080 maps to exactly 2560×1440 — and why 1920×1080 content scales cleanly to 4K (factor 2.0) but not to 1440p without uneven pixel mapping.
Aspect Ratio Is Just a Reduced Fraction
The aspect ratio of a screen is its width divided by its height reduced to lowest terms using the greatest common divisor. 1920 x 1080 shares a divisor of 120, which leaves 16:9. 2560 x 1080 reduces to 64:27, usually marketed as 21:9.
Scaling a size while keeping the ratio is a single multiplication: new height = new width x (original height / original width). That is how you find the matching height for a 1280-pixel-wide embed or check whether a banner will be cropped on an ultrawide display. If the reduced ratio looks odd, such as 683:384, the source dimensions are slightly off from a standard format.
How the Calculation Works
- Computes Greatest Common Divisor (GCD) using Euclidean algorithm to simplify ratios.
Worked Example
Common Questions
Why is 21:9 actually 43:18?
3440x1440 simplifies to 43:18. "21:9" is a consumer marketing approximation.
How do I scale to an exact resolution?
Multiply or divide both width and height by the same factor to keep the simplified ratio constant. For progressive scaling from 1080p to 1440p the multiplier is 1440/1080 = 1.333.
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