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Aspect Ratio Calculator

Enter a width and height to reduce them to their simplest ratio — 1920 × 1080 becomes 16:9. Then enter a new width to get the height that keeps the same shape, so images and video resize without stretching.

Quick examples

Gives the height that keeps the same shape.

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Aspect ratio16:9
As a decimal (width ÷ height)
1.7778
New height
720
Megapixels
2.07 MP

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      Formula

      Aspect ratio = width ÷ GCD : height ÷ GCD, where GCD is the greatest common divisor
      New height = new width × height ÷ width
      New width = new height × width ÷ height

      How to use it

      1. Enter the original width and height in pixels or any unit.
      2. Read the simplified ratio and its decimal value.
      3. Enter a new width to get the matching height.

      Worked examples

      1920 × 1080, resized to 1,280 wide

      Aspect ratio
      16:9
      As a decimal (width ÷ height)
      1.7778
      New height
      720
      Megapixels
      2.07 MP

      2560 × 1600 (sold as 16:10), resized to 1,000 wide

      Aspect ratio
      8:5
      As a decimal (width ÷ height)
      1.6
      New height
      625

      A 4032 × 3024 phone photo, resized to 1,200 wide

      Aspect ratio
      4:3
      New height
      900
      Megapixels
      12.19 MP

      Common ratios and resolutions

      16:9 is the standard for TV and online video: 1280 × 720, 1920 × 1080, 2560 × 1440 and 3840 × 2160. 4:3 covers older screens and many phone photos (1024 × 768, 4032 × 3024). 3:2 is the shape of most DSLR photos, 1:1 is square, and 9:16 is vertical video.

      Marketing names are rounded

      The mathematically reduced ratio is not always the name on the box. 2560 × 1600 reduces to 8:5 and is sold as 16:10. “21:9” ultrawide monitors are really 64:27 (2560 × 1080) or 43:18 (3440 × 1440), both close to 21:9 but not exactly it.

      Questions people ask

      What is the aspect ratio of 1920 × 1080?

      16:9. Both numbers divide by 120, giving 16 and 9.

      What height keeps 16:9 at 1,280 pixels wide?

      720 pixels: 1,280 × 9 ÷ 16.

      How do I find the new width from a new height?

      Multiply the new height by the decimal ratio. For 16:9 at 1,440 high: 1,440 × 1.7778 = 2,560 wide.

      Related calculators

      Screen Size CalculatorWidth, height and area of a screen from its diagonal.PPI CalculatorPixel density of a screen from its resolution and diagonal.Pixels to Inches CalculatorConvert pixel dimensions to inches or cm at any PPI.Ratio CalculatorSimplify a ratio and split a total in that ratio.GCF CalculatorGreatest common factor of two or more whole numbers.