Enter your original width and height, then provide either a new width or new height — the Aspect Ratio Calculator solves for the missing dimension while preserving your exact proportions. You also get the simplified ratio (e.g. 16:9) and the nearest standard display ratio as secondary outputs.
Aspect Ratio
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Solved Width (W2)
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Solved Height (H2)
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Ratio (W÷H)
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Nearest Standard Ratio
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An aspect ratio is the proportional relationship between a rectangle's width and height, expressed as two numbers separated by a colon (e.g. 16:9). It describes shape, not absolute size — a 1920×1080 screen and a 1280×720 screen both share the 16:9 ratio.
Divide both the width and height by their greatest common divisor (GCD). For example, 1920 and 1080 share a GCD of 120, so 1920÷120 = 16 and 1080÷120 = 9, giving 16:9. You can also express it as a single decimal by dividing width by height (1920÷1080 ≈ 1.7778).
Use the formula: new height = (original height ÷ original width) × new width. For example, if your original image is 1600×1200 and you want a new width of 400, the new height = (1200 ÷ 1600) × 400 = 300 pixels. The reverse applies for finding a new width from a known height.
The most widely used ratios are 16:9 (HD and 4K video, most monitors), 4:3 (older TVs and standard definition), 1:1 (square, used on Instagram), 9:16 (vertical/mobile video), 21:9 (ultrawide monitors), and 3:2 (DSLR photography). Digital cinema uses ratios like 2.35:1 or 2.39:1.
Aspect ratio is used whenever you need to resize, crop, or adapt media without distortion — including resizing photos for websites, exporting video for different platforms, setting dimensions for UI/UX design, configuring display resolutions, and ensuring ad creatives fit placement requirements across social media.
'Fit' scales your content to stay entirely within the target frame, which may add letterbox or pillarbox bars (black padding) on the sides. 'Fill' scales content to cover the entire target frame, which may crop parts of the image. Choose fit to preserve all content; choose fill to avoid empty borders.
No — aspect ratio is a dimensionless proportion, so the unit (pixels, inches, centimeters) doesn't matter as long as both width and height are measured in the same unit. A photo that is 6 inches × 4 inches has the same 3:2 ratio as one that is 3000 px × 2000 px.
A 1920×1080 image has an aspect ratio of 16:9. This is the standard widescreen ratio used for HD and Full HD video, most modern monitors, YouTube, and broadcast television.