MeasureSparkScreen & ruler
Screen Size Calculator
Use this to estimate whether a TV or monitor fits a wall, desk, cabinet, or bag.Enter your measurements
Width = diagonal × aspect width divided by the aspect-ratio diagonal.
How this estimate works
Width = diagonal × aspect width divided by the aspect-ratio diagonal.
Measure twice and use the same unit throughout. Product coverage, material density, installation patterns, and local requirements can change the quantity you need.
Quick answer
To find screen width from a diagonal, multiply the diagonal by the aspect-ratio width, then divide by the diagonal of that ratio. A 16:9 screen uses width = diagonal × 16 ÷ √(16² + 9²).
Worked example
A 55-inch 16:9 screen is about 47.9 inches wide and 27.0 inches high. Those are viewable panel dimensions; the bezel, feet, and wall-mount clearance are separate.
Assumptions
- The diagonal describes the visible rectangular panel.
- The entered aspect ratio matches the displayed content area.
- The result excludes the bezel, stand, cables, and installation clearance.
How do diagonal and aspect ratio determine width?
The aspect ratio describes the relative width and height. Treat those two values as the legs of a right triangle, find the ratio diagonal with the Pythagorean theorem, and scale the width leg to the advertised screen diagonal.
Does a 55-inch TV measure 55 inches wide?
No. The advertised size is measured diagonally across the viewable screen. A typical 16:9 55-inch panel is just under 48 inches wide before the frame is added.
What should I use for a fit check?
Use the calculated panel size for an early comparison, then use the exact model's published overall width, height, stand footprint, ventilation clearance, and mounting pattern before buying or installing it.
Where are common 16:9 sizes listed?
The screen size chart lists formula-derived width and height for diagonals from 13.3 to 98 inches at 16:9. Use it to compare a 24-inch monitor with a 55-inch TV before checking the product sheet for the chassis.
Last reviewed September 22, 2026. Source: W3C Media Queries definition of aspect ratio. Product instructions take priority over a general estimate.
Common questions
Short answers for the measurement details people most often need before using this calculator.
Can I calculate TV width from diagonal screen size?
Yes. Enter the advertised diagonal and aspect ratio to calculate the visible screen width. The bezel and stand are not included.
Is screen size the same as viewing distance?
No. This tool calculates physical screen dimensions. Comfortable TV or monitor viewing distance also depends on resolution, eyesight, room layout, and personal preference.
How wide is a 55-inch 16:9 TV?
The visible panel is about 47.9 inches wide and 27.0 inches high. The bezel, stand, and wall-mount clearance are extra. See the 16:9 chart for other common diagonals.