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Input TV diagonal inches, instantly calculate screen width, height, area and recommended viewing distance.
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
A TV's advertised size is its screen diagonal, measured corner to corner. Enter that diagonal in inches and choose an aspect ratio to calculate the ideal screen width, height, and area. Or switch to width-and-height mode, enter both screen dimensions in centimeters, and solve for the diagonal.
An aspect ratio such as 16:9 describes width compared with height. If the ratio is a:b and diagonal D is in inches, the screen rectangle follows the Pythagorean relationship:
Width (cm) = 2.54 × D × a / √(a² + b²)
Height (cm) = 2.54 × D × b / √(a² + b²)
Area (cm²) = width × height
For known dimensions: D (inches) = √(width² + height²) / 2.54
The factor 2.54 converts inches to centimeters. The preset ratios are 16:9, 4:3, 21:9, and 16:10; custom mode accepts a positive width-to-height ratio.
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Keep diagonal mode selected and enter the screen size in inches, as listed by a manufacturer.
Choose a preset or select custom and enter both ratio values. For example, 16 and 9 represent a 16:9 rectangle.
Review diagonal, width, height, and area. Set display precision from zero to four decimal places; this changes only how the result is shown.
Select dimensions mode and enter positive screen width and height in centimeters. The calculator returns the diagonal and area from those two measurements.
For a reproducible check, a 55-inch 16:9 screen has an ideal width of about 121.8 cm and height of about 68.5 cm. Multiplying those rounded dimensions gives about 8,343 cm²; the unrounded calculation may differ slightly.
Use cases
See how the tool fits into real work and everyday tasks.
Calculate the likely screen width, then compare it with the usable surface. Leave room for the actual set and its feet, rather than treating screen width as the complete footprint.
Use the same ratio and precision for two advertised diagonals to compare their display rectangles. Check the product's specification sheet before ordering.
If you know the visible width and height of the existing screen, dimensions mode can estimate its diagonal. Measure the illuminated screen area, not the outside of the housing.
Q&A
Find concise answers to common questions and confusing cases.
No. The result is the ideal rectangular screen area. A TV's outer dimensions and installation space depend on its specific enclosure, feet, and mounting arrangement.
A diagonal alone does not determine a unique width and height. The ratio supplies the rectangle's shape; a wider ratio produces a wider, shorter screen at the same diagonal.
The geometry works for any rectangular display surface when you know its diagonal and aspect ratio, or its width and height. It does not assess image quality or installation requirements.
Notes
Review scope, result limitations, and important precautions before use.
This is a mathematical estimate of a rectangular visible screen, not a model-specific product drawing. The reverse mode uses the two dimensions you enter and does not infer a ratio. Use the manufacturer's measurements for cabinet fit, stand footprint, wall mounts, and clearance.
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