Free Screen Size Calculator

Understanding Display Dimensions

When you’re evaluating a new monitor, television, or smartphone, the display’s physical dimensions—height, width, and area—are often more informative than the diagonal measurement alone. A screen size calculator takes the diagonal and aspect ratio and instantly computes all relevant screen dimensions, whether the display is flat or curved. This display size calculator eliminates manual calculations and helps you make informed decisions about fitting a screen into a specific space or comparing different models.

What Aspect Ratio Tells You

The aspect ratio (AR) describes how width relates to height in a rectangular display. Common ratios include 16:9 (most HDTVs), 4:3 (older monitors), 21:9 (ultrawide), and 2.17:1 (some smartphones). An aspect ratio calculator can help explore the proportions, but AR alone does not define the actual size—a 16:9 label applies equally to a 55‑inch TV and a 6‑inch phone. To get precise monitor size or TV screen size values, you must combine the aspect ratio with the diagonal measurement.

The Math Behind the Screen

All flat‑screen geometry rests on three basic relationships from algebra and trigonometry:

• Pythagorean theorem: $$\text{diagonal}^{2} = \text{height}^{2} + \text{width}^{2}$$
• Aspect ratio definition: $$AR = \dfrac{\text{width}}{\text{height}}$$
• Rectangle area: $$\text{area} = \text{width} \times \text{height}$$

From these, we can solve for height and width directly:

$$\text{height} = \dfrac{\text{diagonal}}{\sqrt{AR^{2} + 1}}, \qquad \text{width} = AR \times \text{height}$$

With these equations, any monitor size calculator can deliver height, width, and area in a fraction of a second.

How to Use the Screen Size Calculator

Using this online tool is simple:

1. Pick the aspect ratio – choose from presets like 16:9, 16:10, 21:9, 4:3, or enter a custom ratio (e.g., 2.17:1).
2. Enter the diagonal – type the diagonal length in inches, centimeters, or any consistent unit.
3. Read the results – the tool displays height, width, and area for flat screens. For curved displays, you also provide the curvature rating (e.g., 1800R) and then receive the base width and base depth alongside the standard dimensions.

This process gives you a full set of screen dimensions without any manual math.

Real‑World Example: Smartphone Showdown

Let’s compare two iPhones: the iPhone X (5.85″ diagonal, 2.17:1 aspect ratio) and the iPhone 8 Plus (5.5″ diagonal, 16:9 aspect ratio). Although the iPhone X has a larger diagonal, its narrower ratio means the viewing area is nearly the same.

Using the formulas:

iPhone X

\begin{aligned} \text{height} &= \frac{5.85}{\sqrt{2.17^{2} + 1}} = \frac{5.85}{\sqrt{4.7089 + 1}} = \frac{5.85}{\sqrt{5.7089}} \approx \frac{5.85}{2.389} \approx 2.45\ \text{in},\$$4pt] \text{width} &= 2.17 \times 2.45 \approx 5.32\ \text{in},\$$4pt] \text{area} &= 2.45 \times 5.32 \approx 13.0\ \text{in}^{2}. \end{aligned}

iPhone 8 Plus

\begin{aligned} \text{height} &= \frac{5.5}{\sqrt{(16/9)^{2} + 1}} = \frac{5.5}{\sqrt{\frac{256}{81} + 1}} = \frac{5.5}{\sqrt{\frac{337}{81}}} = \frac{5.5 \times 9}{\sqrt{337}} \approx \frac{49.5}{18.36} \approx 2.70\ \text{in},\$$4pt] \text{width} &= \frac{16}{9} \times 2.70 \approx 4.80\ \text{in},\$$4pt] \text{area} &= 2.70 \times 4.80 \approx 12.96\ \text{in}^{2}. \end{aligned}

Phone	Diagonal (in)	Aspect Ratio	Height (in)	Width (in)	Area (in²)
iPhone X	5.85	2.17:1	2.45	5.32	13.0
iPhone 8 Plus	5.5	16:9	2.70	4.80	12.96

The diagonal of the iPhone X is 6.3% larger, yet its screen area is only about 0.3% bigger. The aspect ratio dramatically affects how the screen dimensions translate into usable area.

Curved Screens: Extra Considerations

Curved monitors and TVs introduce a curvature rating, usually given in millimeters (e.g., 1800R). A smaller number means a tighter curve. The geometry of a curved screen follows the same height and arc‑length formulas as a flat screen, but you also need to calculate the straight‑line width and depth.

Assuming the screen width represents the arc length of a circle with the given curvature radius, the additional measures are:

• Base width (the chord width): $$\text{base width} = 2 \times \text{radius} \times \sin\left(\frac{\text{length}}{2 \times \text{radius}}\right)$$
• Base depth (the projection from the chord center): $$\text{base depth} = \text{radius} \times \left(1 - \cos\left(\frac{\text{length}}{2 \times \text{radius}}\right)\right)$$

These values help you understand how much space a curved TV screen size actually occupies on a wall or desk. The screen size calculator handles both flat and curved cases, requiring only the curvature rating as an extra input for curved displays.

Why Use This Tool?

Manually applying the Pythagorean theorem and trigonometric functions is tedious and prone to errors. A dedicated screen size calculator provides instant, accurate results for any display type—flat or curved. Whether you are selecting a monitor size, comparing TV screen size options, or simply curious about your phone’s screen dimensions, this tool delivers height, width, area, and (for curved models) base width and depth in one go. Make your next purchase or setup decision with complete spatial awareness, without reaching for a calculator.