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Aspect Ratio Calculator

Developer Tools

Resize a video, image or canvas to any aspect ratio and get the missing width or height plus the megapixel count.

Your inputs

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For 16:9 the left side is 16.

For 16:9 the right side is 9. Use 2.35 : 1 for cinema scope.

Result

Missing side — px
  • Aspect ratio —
  • Ratio as a decimal —
  • Total pixels — MP

Change any input and the result updates instantly.

Formula and rules

  • Height = width × right side ÷ left side
  • Width = height × left side ÷ right side
  • Decimal ratio = left side ÷ right side, so 16:9 is 1.7778
  • Megapixels = width × height ÷ 1,000,000

Worked examples

1080p from a 1920 width

Input Ratio 16:9, width 1920 px.

Result Height 1080 px, decimal ratio 1.7778, 2.07 megapixels.

A 4:3 photo at 1080 tall

Input Ratio 4:3, height 1080 px.

Result Width 1440 px, ratio 1.3333, 1.56 megapixels.

Ultrawide 21:9 at 2520 wide

Input Ratio 21:9, width 2520 px.

Result Height 1080 px, ratio 2.3333, 2.72 megapixels.

FAQ

What ratio is 1920 × 1080?

Divide both sides by 120 and you get 16:9, the standard widescreen ratio. 1280 × 720 and 3840 × 2160 share it, which is why they are called 720p and 4K UHD.

Why is the result not a whole number?

Ratios rarely divide evenly. For video and images, round to the nearest even number before encoding, because most codecs prefer even dimensions for chroma subsampling.

Does this affect DPI or print size?

No. This tool only converts width and height at a fixed ratio. Print size also depends on DPI: inches = pixels ÷ DPI, so a 3000 px wide photo is 10 inches at 300 DPI.

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Disclaimer: Results follow the formula shown on this page and are for reference only. Real-world quantities vary with materials, technique and conditions, so allow a margin before ordering.