Screen Area Calculator: Free Screen Size Calculator
Screen Area Calculator. Enter a diagonal and aspect ratio in this screen area calculator to get the viewable area in square inches and centimeters. Use the free px to rem converter to switch units in one click — no install or account needed.
Interactive Tool
The Screen Area Calculator works out the actual viewable surface of a display in square inches and square centimeters, because diagonal size alone can be misleading once aspect ratio changes. Enter a diagonal size and pick an aspect ratio, and you'll get the physical width, height, and screen area — add a second diagonal and ratio and the tool shows you the area difference as a percentage. It's how you find out that a 27-inch 16:9 monitor and a 27-inch 21:9 ultrawide, despite sharing a diagonal, don't actually give you the same amount of screen.
A TV box says 43-inch, but that is only the diagonal, and it says nothing about how much picture you get. The Screen Area Calculator (sq inches) turns a diagonal and an aspect ratio into the width, height and total area in square inches. Use it to compare monitor size, phone screen dimensions or any display before you measure the wall or buy.
How the Screen Area Calculator (sq inches) Works
This online screen size calculator treats every panel as a rectangular display. Pick a ratio (or choose custom and type one, such as 2.4:1), enter the diagonal, and it returns the width, height and viewable area in in². The screen area calculator (sq inches) works the same for a smartphone, a tablet, a laptop or a wall-sized screen, because the geometry doesn't change with size. Given width and height, it also runs as a screen dimensions calculator in reverse. Use the monitor viewing distance calculator any time you need a fast, accurate figure without doing the arithmetic yourself.
Inputs: Screen Diagonal and Aspect Ratio
The screen diagonal runs corner to corner across the visible picture, never the bezel. If the box doesn't list it, use a tape measure from a lower corner to the opposite upper corner. The aspect ratio is width divided by height; pick the screen shape that matches yours.
Screen Dimensions Formula for Screen Width, Height and Area
Call the aspect ratio width a, the aspect ratio height b and the diagonal d. The screen size formula scales the ratio triangle up to the real diagonal:
$$W = \frac{a \times d}{\sqrt{a^{2} + b^{2}}} \qquad H = \frac{b \times d}{\sqrt{a^{2} + b^{2}}}$$
With the width and the screen height known, the area is the area of a rectangle, so you multiply the two:
$$A = W \times H = \frac{a \times b \times d^{2}}{a^{2} + b^{2}}$$
The square root drops out, which shows why any screen width and height calculator gives an area that grows with the diagonal squared.
Worked Example: A 43-Inch 16:9 TV
Suppose you're weighing a 43-inch TV for a small living room wall:
- √(16² + 9²) = √337 = 18.358
- Width = 16 × 43 ÷ 18.358 = 37.48 in
- Height = 9 × 43 ÷ 18.358 = 21.08 in
- Area = 37.48 × 21.08 = 790.1 sq in
That is about 37½ by 21 in of wall space before the frame, or 5.49 square feet of picture. Those numbers decide whether the TV fits between two shelves.
Pythagorean Theorem and the Diagonal Measurement
The formulas come from the Pythagorean theorem, d² = W² + H². Run it backwards and 37.48² + 21.08² = 1,849, whose root is 43, the diagonal measurement you started with. A diagonal screen size calculator does exactly this.
How Aspect Ratio Changes Screen Size at the Same Diagonal
Two screens with the same diagonal can differ a lot in area, because the proportion of width to height changes how the diagonal splits. An aspect ratio screen size calculator makes this obvious: The free monitor desk depth calculator breaks the math down step by step so the answer is never a black box.
| Aspect ratio (43-inch) | Width (in) | Height (in) | Area (sq in) |
|---|---|---|---|
| 16:9 | 37.48 | 21.08 | 790.1 |
| 16:10 | 36.46 | 22.79 | 831.0 |
| 21:9 | 39.52 | 16.94 | 669.5 |
| 4:3 | 34.40 | 25.80 | 887.5 |
Widescreen, Ultrawide and 4:3 Compared
The squarer the shape, the more area per inch of diagonal. The old CRT and iPad shape gives 12% more picture than the TV standard, while a 21:9 computer monitor gives 15% less despite being the widest. Widescreen 16:10 sits between them, which is why many laptops use it.
Screen Size Comparison: Why the Diagonal Misleads
Stores line displays up by diagonal, so moving up from a 43-inch LCD looks like a small step. It isn't. A narrow 11-inch Android tablet and a squarer 11-inch slate don't share the same display size either. Comparing area is the honest way to compare screen size.
Area Grows With the Square of the Diagonal
Because area scales with d², the gaps widen fast. A 58-inch TV has about 1,437 sq in of picture, 1.82 times the 43-inch set, and a 75-inch reaches 2,404 sq in, over three times as much. A TV screen size calculator turns a vague "bigger" into a measurement you can picture.
Checking Monitor Size Before Swapping Two Screens for One Ultrawide
I'm deciding whether to replace two 23.8-inch 16:9 monitors with one 37.5-inch 24:10 ultrawide, and the question is simple: do I lose working space? The answer: no, the single screen gains about 3% screen area, but it gives up width and gains height.
I enter 23.8 in with 16:9 first. The calculator returns 20.74 × 11.67 in and 242.0 sq in, so the pair gives 484.1 sq in. Then I switch the ratio to custom 24:10 and enter 37.5: 34.62 × 14.42 in, 499.3 sq in. To cross-check, I square both sides of the ultrawide by hand: 34.62² + 14.42² = 1,406.2, and its root is 37.5, so the numbers hold.
| Setup | Width (in) | Height (in) | Area (sq in) |
|---|---|---|---|
| Two 23.8-inch 16:9 | 41.49 | 11.67 | 484.1 |
| One 37.5-inch 24:10 | 34.62 | 14.42 | 499.3 |
| One 34-inch 3440 × 1440 | 31.36 | 13.13 | 411.8 |
The rerun with a 34-inch model is the useful one: it drops to 411.8 sq in, 15% less than my current pair. Solving the formula for break-even, a 24:10 screen needs a 36.93-inch diagonal just to match two 23.8-inch monitors, so anything 34-inch is a downgrade in area.
One trap: the "21:9" label on a 3440 × 1440 panel is really 43:18. Entering 21:9 gives 418.6 sq in instead of 411.8, a 7 sq in error from rounding the ratio. Enter the exact pixel ratio when you have it.
Area settles the space question, so the next check is how that area is filled. The ultrawide's 3840 × 1600 pixels come to 110.9 PPI, against 92.6 PPI now and the 96 PPI Windows treats as 100% scaling, so at about 115% scaling text stays the same size and gets sharper. Given that, plus the extra 2.75 in of height, the 37.5-inch display is the one I'm ordering, and the side-by-side bezel gap disappears as a bonus.
Measuring a Curved Screen With a Display Size Calculator
A curved screen is measured along the glass with the tape touching the surface, so the calculator's answer holds: a 34-inch 2.33:1 display covers 418.6 sq in, curved or flat. What changes is the footprint. Treat the width as an arc length on a circle of radius r:
$$\text{base width} = 2r\sin\left(\frac{W}{2r}\right) \qquad \text{base depth} = r\left(1-\cos\frac{W}{2r}\right)$$
At 1500R, that display's 31.25 in arc spans a 30.89 in base width and bows 2.06 in toward you.
What the Curvature Rating Means
The curvature rating is that circle's size in millimetres: 1500R means the display follows a 1,500 mm (about 59 in) radius. A lower number means a tighter curve and a deeper base, but never a different square-inch area.
Viewing Distance and Resolution Beyond the Screen Size Calculator
Area tells you how much picture you get; viewing distance and resolution tell you whether it's the right amount. An ideal screen size fills your view without exceeding what your visual acuity can resolve. Audiovisual designers sizing a display for conference rooms tie the farthest seat to image height, and a screen size distance calculator applies that idea at home.
Pixel Density, PPI and Screen Size
Spread the same pixel resolution over more area and each pixel grows. A 4K display at 43 in packs about 102 PPI; Full HD on the same screen size drops to about 51, enough to see pixelation at a desk. Pixel density decides sharpness up close.
Living Room and Home Theater Sizing
The optimal screen size depends on where you sit. Distant home theater seats may need the 1,437 sq in of a 58-inch set where 790.1 sq in feels small, so compare candidates by area before deciding how much viewing experience the room can hold.
Converting Units for the Area of the Screen
Divide the area of the screen by 144 for square feet, or take it times 6.4516 for square centimetres. The example's 790.1 sq in is 5.49 sq ft or about 5,097 cm². Starting from centimetres, divide each side by 2.54 first.
Projector Screen Size Calculator Tips for Home Cinema
A projector has no fixed diagonal; image size depends on throw distance, so plan from the screen you'll hang. The same lumens spread over a larger projector screen give a dimmer picture: a 110-inch 16:9 screen has 5,170 sq in against 3,461 sq in at 90 in, so brightness per square inch drops by a third, which is why big home cinema screens need dark rooms to beat ambient light. Size the screen with this free screen size calculator, then pick a projector that can light it.
Frequently Asked Questions
- How do I calculate the area of a screen in square inches?
- Find the width and height in inches and multiply them. If you only know the diagonal d and the aspect ratio a:b, width = a × d ÷ √(a² + b²) and height = b × d ÷ √(a² + b²), so area = a × b × d² ÷ (a² + b²). A 43-inch 16:9 screen works out to about 790.1 sq in.
- How do I find a screen's diagonal from its width and height?
- Square the width and the height, add them, and take the square root. This is the Pythagorean theorem, because the diagonal is the hypotenuse of the right triangle formed by the two sides.
- Does the aspect ratio change the screen area?
- Yes. At the same diagonal, a squarer screen has more area. At 43 inches, a 4:3 screen has about 887.5 sq in, a 16:9 screen about 790.1 sq in and a 21:9 ultrawide about 669.5 sq in.
- Is a screen with double the diagonal twice as big?
- No, it has four times the area. Area grows with the square of the diagonal, so even a modest increase in diagonal adds a lot of picture.
- How is a curved screen measured?
- Measure the diagonal along the glass with the tape touching the surface, just like a flat screen. The area is the same as a flat screen with that diagonal and ratio. The curve only makes the base narrower and adds depth, which depends on the curvature rating.
- What does a curvature rating like 1800R mean?
- It is the radius of the circle the screen follows, in millimetres. 1800R means a radius of 1,800 mm. A smaller number is a tighter curve with a deeper base.
- How do I convert square inches to square feet or cm²?
- Divide square inches by 144 to get square feet, or multiply by 6.4516 to get square centimetres.