Screen Size Calculator
Calculate the physical width and height of a screen from its diagonal measurement and aspect ratio.
Diagonal measurement of the screen
Minimum: 0
Width component of the aspect ratio (e.g., 16 for 16:9)
Minimum: 0
Height component of the aspect ratio (e.g., 9 for 16:9)
Results
Screen Width
23.53 inches
Screen Height
13.24 inches
Screen Area
311.5 sq in
How to Use This Calculator
Enter your input values
Fill in all required input fields for the Screen Size Calculator. Follow the units and input format printed next to each field. Where a unit selector is available, choose the units that match your data.
Review your inputs
Double-check that all values are correct and match the units or format shown for each field. Incorrect units are the most common source of calculation errors and can produce results that are off by factors of 2, 10, or more.
Read the results
The Screen Size Calculator computes the output in your browser and displays the results, with units clearly labeled, as soon as they are ready — no data sent to a server.
Explore parameter sensitivity
Try adjusting individual input values to see how the output changes. This is a quick and effective way to develop intuition about how different parameters influence the result and to identify which inputs have the largest effect.
When to Use This Calculator
- •Use the Screen Size Calculator when you need accurate results quickly without the risk of manual computation errors or unit conversion mistakes.
- •Use it to verify calculations made by hand or in spreadsheets — an independent check can catch errors before they lead to costly decisions.
- •Use it to explore how changing input parameters affects the output — a quick way to develop intuition and identify the most influential variables.
- •Use it when collaborating with others to ensure everyone is working from the same numbers and applying the same assumptions.
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About Screen Size Calculator
The Screen Size Calculator converts a diagonal screen measurement and aspect ratio into physical width and height dimensions. Screen sizes are always advertised as diagonal measurements, which makes it difficult to compare screens with different aspect ratios. A 32-inch 16:9 monitor and a 32-inch 21:9 ultrawide have very different actual widths and heights. This calculator reveals the true dimensions so you can plan your desk setup, wall mount placement, or compare display sizes accurately.
The Math Behind It
Formula Reference
Screen Dimensions from Diagonal
Width = D * W_r / sqrt(W_r^2 + H_r^2), Height = D * H_r / sqrt(W_r^2 + H_r^2)
Variables: D = diagonal, W_r = aspect ratio width, H_r = aspect ratio height
Worked Examples
Example 1: 27-inch 16:9 monitor dimensions
A 27-inch monitor with a 16:9 aspect ratio.
The screen is approximately 23.53 inches wide by 13.24 inches tall with 311.5 square inches of area.
Common Mistakes & Tips
- !Assuming diagonal size directly indicates viewable area; a 32-inch 16:9 and 32-inch 21:9 have very different areas.
- !Forgetting that advertised sizes may include the bezel on some older displays.
- !Confusing aspect ratio components (entering 9:16 instead of 16:9).
Related Concepts
Used in These Calculators
Calculators that build on or apply the concepts from this page:
Frequently Asked Questions
Why are screens measured diagonally?
The convention originated with round CRT tubes where the diameter (diagonal) was the natural measurement. The tradition continued with flat screens as a convenient single number to represent size.
Is a bigger diagonal always more screen area?
Not necessarily when comparing different aspect ratios. A 27-inch 16:9 has about 311 sq inches while a 29-inch 21:9 has about 294 sq inches. The wider ratio redistributes the area despite a larger diagonal.
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