How screen size is measured
A screen's advertised size normally refers to its diagonal measurement, not its width. Two screens can therefore have the same diagonal size but different widths and heights when their aspect ratios differ.
Screen width and height formula
If the diagonal and aspect ratio are known, the physical dimensions can be calculated using the Pythagorean theorem.
Example: 27-inch 16:9 screen
For a 27-inch screen with a 16:9 aspect ratio, the physical display dimensions are approximately:
Width: 23.53 inches
Height: 13.24 inches
That is approximately 59.77 cm wide and 33.62 cm high.
Calculate diagonal from width and height
If the physical screen width and height are known, the diagonal follows directly from the Pythagorean theorem.
This is useful when measuring a display directly and checking its approximate advertised diagonal size.
Screen area
Screen area is the physical area of the rectangular display surface.
Area can be useful when comparing displays with different aspect ratios because equal diagonal sizes do not always provide equal display area.
Screen perimeter
Perimeter is the distance around the calculated screen rectangle. It does not include the physical bezel or external dimensions of a monitor, television, laptop or device.
Common screen aspect ratios
The calculator includes several common presets:
16:9 is widely used for TVs, monitors, video and many laptop displays.
16:10 provides slightly more vertical space than 16:9 and is common on some productivity displays and laptops.
4:3 is a traditional display ratio used by many older monitors and televisions.
3:2 is used by some laptops, tablets and productivity displays.
21:9 and 32:9 are common descriptions for ultrawide and super-ultrawide screen formats.
Custom aspect ratios
You are not limited to the presets. Select Custom ratio and enter any positive width and height ratio values.
For example, 18:10 and 9:5 describe the same proportional shape because both simplify to a ratio of 1.8:1.
Inches and centimeters
Screen diagonals are frequently marketed in inches even in countries that otherwise use metric measurements.
This calculator supports both inches and centimeters and also shows the calculated physical dimensions in both systems.
Same diagonal, different shape
A 16:9 screen and a 4:3 screen with the same diagonal do not have the same width, height or area. The wider screen uses more of its diagonal horizontally, while the less wide screen uses more of it vertically.
This is why diagonal size alone is not enough when deciding whether a display will fit a desk, cabinet, wall opening or other physical space.
Visible screen vs. device size
The calculator estimates the visible rectangular screen dimensions. A real product is usually larger because of bezels, chassis, hinges, stands and other hardware.
Always check the manufacturer's full product dimensions when fitting a monitor or television into a limited physical space.
Screen size vs. resolution
Physical screen size and pixel resolution are different measurements. Two 27-inch screens can have the same physical dimensions while using very different resolutions.
To calculate pixel density from physical screen size and pixel resolution, use the PPI Calculator.
Related digital calculators
To calculate or simplify image and display proportions, use the Aspect Ratio Calculator.
To calculate physical print dimensions from pixel size and resolution, use the Print Size Calculator.
For pixel density, use the PPI Calculator.
Results describe the rectangular screen area implied by the entered diagonal and aspect ratio. They do not include bezels, housings, stands or other device dimensions.
Frequently asked questions
How wide is a 27-inch 16:9 monitor?
The visible screen is about 23.53 inches wide and 13.24 inches high.
Is screen size measured diagonally?
Yes. The commonly advertised screen size is generally the diagonal measurement of the visible display area.
Does a 32-inch TV have a width of 32 inches?
No. The 32-inch measurement refers to the diagonal. The width depends on the aspect ratio.
Can I calculate diagonal size from width and height?
Yes. Select the reverse mode and enter the physical width and height.
Does this calculator include the bezel?
No. It calculates the rectangular display area, not the outer dimensions of the device.
Using this calculator effectively
The Screen Size Calculator converts diagonal display size and aspect ratio into physical width, height, area and perimeter. It can also calculate diagonal size and approximate aspect ratio from measured width and height.
Common uses
- Checking the physical width and height of a monitor or television before buying or installing it.
- Comparing screens with the same diagonal but different aspect ratios.
- Calculating an approximate diagonal size from measured screen width and height.
Tips for a better estimate
- Use the visible display diagonal rather than the full device or bezel dimensions.
- Select the correct aspect ratio or enter custom ratio values when using diagonal-to-dimensions mode.
- For installation planning, verify the manufacturer's complete outer product dimensions because this calculator does not include bezels or stands.
Related calculations
Aspect Ratio Calculator · Audio File Size Calculator · Download Time Calculator