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Screen size calculator

Compute a screen's width and height in cm from its diagonal and aspect ratio.

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The Screen size calculator turns Diagonal (inches), Aspect ratio into Width (cm), Height (cm), instantly and for free. For instance, with Diagonal (inches) = 27 and Aspect ratio = 16:9 it returns Width (cm) = 59.773 and Height (cm) = 33.622.

How to use it

  1. Enter your values: Diagonal (inches), Aspect ratio.
  2. Read the result instantly: Width (cm), Height (cm).

Frequently asked questions

What does the Screen size calculator actually compute?

It takes Diagonal (inches) and Aspect ratio and derives Width (cm) and Height (cm) from them. The calculation is live as you type, so the result updates on every change.

What information do I need to provide?

2 values: Diagonal (inches) and Aspect ratio. Nothing else is required — no account, no file upload.

Can you show a worked example?

With Diagonal (inches) = 27 and Aspect ratio = 16:9, the calculator returns Width (cm) = 59.773 and Height (cm) = 33.622. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

What happens if I enter larger values?

It moves a lot. Using Diagonal (inches) = 54 and Aspect ratio = 16:10 instead, Width (cm) goes from 59.773 to 116.311 — which is why it is worth testing a few scenarios rather than trusting a single figure.

Which “Aspect ratio” option should I choose?

You can pick between « 16:9 », « 16:10 », « 21:9 », « 4:3 » and « 32:9 ». Each one changes what the calculator works out, so switch and compare — the default is « 16:9 ».

What does it give for smaller values?

Scaled down to Diagonal (inches) = 13.5 and Aspect ratio = 16:9, Width (cm) comes out at 29.886. The relationship is worth checking at both ends before you rely on a single result.

When would I actually use this?

Finding out how big a thing will be before you make it: how many gigabytes an hour of footage takes, how long a file needs on the connection you have, how large a photo prints before it goes soft, what bitrate fits the budget you were given.

What is the most common mistake?

Taking the advertised connection speed as the transfer speed. A 100 Mb/s line is megabits, the file is in megabytes, and the eight-fold difference between them is where most download estimates go wrong — before overhead and contention take their own share.

What is the difference between the Screen size calculator and the Print size calculator?

This one returns Height (cm); the Print size calculator returns Width (inches) and Height (inches). That is the whole difference — open the one whose figure you need.

Is there a tool for the next step?

Screen Resolution Guide is the closest one after this: Get the total pixels, megapixels and aspect ratio of a resolution.

Further reading

All guides →
ExplainerScreen Resolution, Pixel Density, and the Numbers Marketing UsesA diagonal plus an aspect ratio gives you width and height by Pythagoras, and the answer is not what the marketing implies: a 27-inch 21:9 has 16.2% less area than a 27-inch 16:9. Then pixels per degree, which shows the highest-PPI phone is not the sharpest thing you own.ExplainerFrame Rates, Timecode, and the Drop-Frame That Drops NothingFrames = duration × rate is trivial until the rate is 29.97. Non-drop timecode then drifts exactly 3.6 seconds an hour. Drop-frame corrects it by skipping 108 frame numbers — the same 108 — but the correction is not perfect: counting every frame shows a residual of 3.6 milliseconds per hour.ExplainerWhat Are PPI and DPI? Pixel Density for Screen and PrintPPI and DPI both measure density per inch, but one is about screens and the other about print. Learn how to compute pixel density and what Retina really means.ExplainerHow Big Is That Audio File?Uncompressed audio size is exact arithmetic: sample rate × bit depth × channels × seconds ÷ 8. CD audio is 176,400 bytes per second. A 320 kbps MP3, by contrast, is bitrate × duration and does not depend on the sample rate at all — 2,400,000 bytes a minute whether it came from 44.1 or 48 kHz.How-toHow to Estimate Video File Size (Bitrate x Duration)Estimate any video's file size before you export. Learn the bitrate-times-duration formula, why you divide by 8, and how resolution and frame rate change the result.ExplainerWhat Is Bitrate? Bits per Second, CBR vs VBRBitrate is how many bits of data a video or audio stream uses each second. Learn how it sets quality and file size, and the difference between constant and variable bitrate.