Aspect Ratio Calculator Widget

Add an aspect ratio calculator to your video, photography or web-design page. Readers enter a size or pick a common ratio such as 16:9 or 9:16, see the simplified ratio, and work out the matching height or width for any new size.

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Auto follows the visitor's light/dark setting.
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Optional and entirely your choice. The exact line is shown in the code below; it links to the tool with rel="nofollow".
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Starting values
Leave blank to use the widget's defaults. Visitors can still change every value.

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Exactly what your visitors will see

Embed code

<iframe src="https://a2z.tools/embed/w/aspect-ratio-calculator" title="Aspect Ratio Calculator by A2Z Tools" width="100%" height="760" style="border:0;width:100%" loading="lazy" allow="clipboard-write"></iframe>

A plain iframe. Works everywhere, including site builders that strip scripts. Adjust height if your content needs more room.

Works with

How it works

The width and height are divided by their greatest common divisor, the method used by the A2Z Aspect Ratio Calculator page. Decimal sizes are first scaled to whole numbers, so 2.35 x 1 simplifies exactly to 47:20. Screen sizes that are almost a standard ratio, such as 1366 x 768, are shown with their nearest common ratio and how close it is. A resized dimension that is not a whole pixel is flagged with the value to round to, and a table lists common widths at the same ratio.

Calculation method

  • Ratio = W / g : H / g, where g = gcd(W, H)
  • New height = new width x H / W; new width = new height x W / H
  • Closest common ratio = named ratio with the smallest relative difference in W / H, shown when within 2%
  • Decimal inputs are scaled by 10^d (d up to 6 decimal places) before the gcd; resized sizes shown to 2 decimals with the nearest whole pixel

Worked examples

A laptop panel sold as 16:9

Inputs: Width 1366, height 768, new width 1280

Result: 683:384 (1.7786:1); closest common ratio 16:9, within 0.05%; height for width 1,280 = 719.65, round to 720

1366 and 768 share only the factor 2, so the exact ratio is 683:384. It is marketed as 16:9 because 16/9 = 1.7778, a 0.05% difference.

A portrait feed post

Inputs: Preset 4:5, new width 1080

Result: Height for width 1,080 = 1,350

1080 x 5 / 4 = 1350, the 1080 x 1350 size commonly used for portrait feed posts.

A cinema scope frame

Inputs: Width 2.39, height 1, new width 1920

Result: 239:100 (2.39:1); height for width 1,920 = 803.35, round to 803

The decimal is scaled to 239 x 100 before simplifying; 1920 / 2.39 is not a whole number, so the widget says which pixel to round to.

Limitations

  • It works on display (pixel) aspect ratios only; anamorphic video with non-square pixels (pixel aspect ratio other than 1) is not converted.
  • Rounding a resized dimension to a whole pixel slightly changes the ratio, which the widget reports but cannot avoid.
  • It does not crop or resize images - it only calculates sizes.
  • Platform size recommendations (Stories, Reels, feed posts) change; check the network's current help pages before a campaign.

Where publishers use it

  • Video and YouTube guides about 16:9, 9:16 and 1:1 exports
  • Photography sites explaining crop ratios such as 3:2 and 4:5
  • Web-design tutorials on responsive images and embeds
  • Social-media marketing pages listing post and story sizes

Questions

Why does 1366 x 768 show 683:384?

That is its exact simplified ratio. It is within about 0.05% of 16:9, which is why it is sold as a 16:9 screen; the widget shows both.

What if the new height is not a whole number?

The widget shows the exact value and suggests the nearest whole pixel. A tiny rounding changes the ratio by a negligible amount.

Which ratio do vertical videos use?

9:16 - for example 1080 x 1920 for Stories, Reels and Shorts.

Can I use decimal sizes such as 2.39:1?

Yes. Decimal widths and heights are scaled to whole numbers before simplifying, so nothing is rounded away.

Cite or recommend this tool

If you reference this tool in an article, course or documentation, these formats are ready to copy. They are optional - nothing is added to your site unless you paste it.

A2Z Tools Aspect Ratio Calculator
https://a2z.tools/aspect-ratio-calculator

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