Two screens with the same diagonal can have very different areas if their aspect ratios differ.
How to use the Screen Size Calculator
- Diagonal
- Aspect ratio width
- Aspect ratio height
Results update as you type, and every field accepts the units shown in its menu.
How it works
The diagonal is the hypotenuse of a right triangle with the aspect ratio’s proportions.
Tips
- Use the figures printed on your product or its manual when you have them.
- Round quantities up so you are never short.
- Measure twice before you buy anything cut to size.
- Everything runs in your browser – try different values to compare options.
Common mistakes to avoid
- Mixing units (inches and centimetres, mAh and Ah).
- Ignoring efficiency losses and safety margins.
- Treating rules of thumb as exact.
Inputs explained
| Field | What to enter |
|---|---|
| Diagonal | Units: in, cm |
| Aspect ratio width | A number |
| Aspect ratio height | A number |
What each result means
- Width = [Diagonal]×[Aspect ratio width]÷sqrt([Aspect ratio width]^2 + [Aspect ratio height]^2)
- Height = [Diagonal]×[Aspect ratio height]÷sqrt([Aspect ratio width]^2 + [Aspect ratio height]^2)
- Screen area = [Width]×[Height]
Example values
How the main result changes when Diagonal changes and everything else stays at the example values above:
| Diagonal (in) | Width (in) |
|---|---|
| 27.5 | 23.97 |
| 41.25 | 35.95 |
| 55 | 47.94 |
| 68.75 | 59.92 |
| 82.5 | 71.9 |
| 110 | 95.87 |
Formula
Width = diagonal × w ÷ √(w² + h²)Height = diagonal × h ÷ √(w² + h²)Worked example
Inputs — Diagonal: 55 in; Aspect ratio width: 16; Aspect ratio height: 9.
Results — Width = 47.94 in; Height = 26.96 in; Screen area = 1,292.6 in².
Frequently asked questions
How big is a 55-inch TV?
About 47.9 × 27 inches (121.8 × 68.5 cm) for 16:9.
Does the bezel count?
No, the diagonal measures only the visible screen.
What formula does the Screen Size Calculator use?
Width = diagonal × w ÷ √(w² + h²).