Screen Size Calculator (Inches, PPI, Resolution)
Enter the diagonal size and aspect ratio of a monitor, TV or phone to get its width, height and area in cm and inches. Add the resolution to see the PPI, dot pitch and a rough distance at which pixels blend together. You can also work backwards from width and height in cm to the diagonal in inches. To only scale ratios and resolutions, use the Aspect Ratio Calculator; for general length units, try the Unit Converter. Everything runs in your browser and nothing is sent to a server.
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Find size and PPI from the diagonal
Results
- Screen width
- Screen height
- Screen area
- PPI (pixel density)
- Dot pitch
- Distance where pixels blend together (estimate)
- Comfortable distance to see the whole screen (estimate)
Find the diagonal from width and height (cm)
- Diagonal size
- Width × height (inches)
- Closest common ratio
Notes
- Results are ideal values for the visible display area (excluding the bezel). Some products round the advertised diagonal, so measured sizes can differ slightly.
- Viewing distances are estimates: the distance where one pixel subtends one arcminute (20/20 vision), and a common rule of thumb of 1.0 to 1.5 times the diagonal. The right distance varies by person and use.
- PPI is the diagonal pixel count divided by the diagonal in inches. If the screen ratio and the resolution ratio differ, a note tells you the PPI is approximate.
- For curved displays the result uses the straight chord length rather than the length along the curve, so it is an approximation.
Glossary
Diagonal size
The length of the line from one corner of the screen to the opposite corner, in inches. One inch is 2.54 cm. It is the usual way to name a screen size.
PPI (pixel density)
The number of pixels per inch. Higher values look sharper, and for the same resolution a smaller screen has a higher PPI.
Dot pitch
The distance between the centers of neighboring pixels in mm. It equals 25.4 divided by the PPI; smaller means finer.
FAQ
What are the width and height of a 27-inch monitor in cm?
For a 16:9 screen it is about 59.8 cm wide and 33.6 cm tall. The 27-inch diagonal is 68.58 cm, and the width and height follow from the aspect ratio. A 16:10 screen of the same diagonal is about 58.2 cm by 36.3 cm.
How is PPI calculated, and how much is enough?
Divide the diagonal pixel count, √(width² + height²), by the diagonal in inches. A 27-inch 4K screen is about 163 PPI and a 27-inch Full HD screen about 82 PPI. As a rough guide, desktop monitors around 100 PPI and phones above 300 PPI look sharp.
How is the viewing distance estimated?
It shows the distance where one pixel subtends one arcminute (20/20 vision, dot pitch × about 3438) and a comfortable range of 1.0 to 1.5 times the diagonal. Vision and habits vary, so treat the values as estimates.
What if the screen ratio and the resolution ratio differ?
The physical size comes from the ratio you enter, while PPI comes from the diagonal pixel count of the resolution. When they differ the tool shows the gap. With non-square pixels the horizontal and vertical PPI differ, so the value is approximate.
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