Screen Size Calculator
Calculate a screen's actual width and height from its diagonal size and aspect ratio. Optionally add resolution to get pixel density (PPI). Compare two screen sizes to see which has more area.
Quick presets
How to use
- Enter the diagonal screen size in inches (the number TV brands advertise).
- Pick the aspect ratio - 16:9 is the standard for most TVs, monitors, and phones.
- Add the screen resolution (optional) to calculate pixels per inch (PPI).
- Enter a second size to compare how much bigger it is in actual area.
Related tools:
Screen sizes are advertised as a diagonal measurement, which tells you nothing directly about width or height. A 27-inch monitor and a 27-inch TV have very different actual screen dimensions depending on their aspect ratio - a 27-inch 16:9 display is 59.5 x 33.5 cm, while a 27-inch 4:3 display would be significantly squarish.
PPI (pixels per inch) matters for display sharpness. A 1080p screen on a 24-inch monitor is 92 PPI - acceptable for a desktop viewed at arm's length. The same 1080p resolution on a 13-inch laptop screen is 170 PPI - noticeably sharper. Apple retina displays start at about 220 PPI. The calculator derives all physical dimensions and pixel density from the diagonal and resolution inputs.
Frequently Asked Questions
What is a good PPI for a monitor vs laptop vs phone?
Desktop monitors: 90-110 PPI is standard; 140+ is high-density. Laptops: 150-200 PPI. Phones: 300+ PPI is considered Retina quality (the distance you hold a phone means you need higher density than a monitor to avoid visible pixels).
How is screen area calculated?
Using the Pythagorean theorem with the aspect ratio: if diagonal is D and ratio is W:H, then width = D x W / sqrt(W^2 + H^2) and height = D x H / sqrt(W^2 + H^2). Area = width x height.
Why do monitor sizes feel smaller than TV sizes at the same diagonal?
Most monitors are 16:9, giving more horizontal space. Many TVs are also 16:9. The viewing distance is different - you sit 50-70cm from a monitor but 2-4m from a TV. A 43-inch TV and a 27-inch monitor can feel similar in terms of perceived image size because of the different viewing distances.