# Screen Ratio Calculator

URL: https://speedycalculator.com/calculators/other/screen-ratio/
Last updated: 2026-10-30

> The screen ratio calculator finds the aspect ratio of any display from its measured width and height or from its resolution in pixels, names the closest standard format (16:9, 16:10, 21:9, 19.5:9…), and with the diagonal size also gives the pixel density and physical dimensions.

## Inputs

- I know
- Screen width (visible area) (cm, in, mm)
- Screen height (visible area) (cm, in, mm)
- Horizontal resolution (px)
- Vertical resolution (px)
- Diagonal screen size (optional) (in, cm, mm, m)

## Results

- Screen ratio
- Ratio as a decimal (width ÷ height)
- Closest standard format
- Written as x:9
- Written as x:10
- Pixel density
- Resolution
- Physical width
- Physical height
- Diagonal
- Screen area

## Formula

```
Screen ratio = width ÷ height (reduced with the GCD for pixel resolutions) · PPI = √(pixels wide² + pixels high²) ÷ diagonal (in) · width = diagonal × r ÷ √(1 + r²), height = diagonal ÷ √(1 + r²)
```

## Explanation

Every screen – TV, monitor, laptop or phone – has a characteristic shape. Manufacturers quote the diagonal size, but two screens with the same diagonal can look very different: a 27-inch 16:9 monitor is about 59.8 × 33.6 cm, while a 27-inch 4:3 screen would be 54.9 × 41.1 cm. Knowing the ratio helps you choose wallpapers, set up video export and judge whether letterbox bars will appear.

There are two ways to find it. With a tape measure, divide the visible width by the visible height and compare the result with the common formats: 1.78 is 16:9, 1.6 is 16:10, 1.33 is 4:3 and about 2.37 is "21:9". With the resolution from your display settings, the pixel numbers reduce exactly – 2560 × 1440 is 16:9 and 2340 × 1080 is 13:6, which phone makers call 19.5:9.

Add the diagonal in the resolution mode to get the pixel density in pixels per inch and the physical width and height, handy for comparing sharpness or checking whether a screen fits a space.

### How to use the Screen Ratio Calculator

- **I know**
- **Screen width (visible area)**
- **Screen height (visible area)**
- **Horizontal resolution (px)**
- **Vertical resolution (px)**
- **Diagonal screen size (optional)**

Everything is calculated in your browser, so results appear instantly and nothing you type is sent to a server.

### How it works

The width is divided by the height. For pixel resolutions the two numbers are reduced by their greatest common divisor; for measurements the decimal ratio is matched to the nearest standard format. PPI divides the diagonal in pixels by the diagonal in inches.

### Worked example

A 27-inch monitor runs at 2560 × 1440. gcd(2560, 1440) = 160, so the ratio is 16:9. Its diagonal is √(2560² + 1440²) = 2937 px, giving 2937 ÷ 27 = 108.8 PPI. Physical width = 27 × 1.778 ÷ √(1 + 1.778²) = 23.5 in (59.8 cm) and height 13.2 in (33.6 cm).

### Screen ratios in practice

RatioDecimalTypical devices4:31.33iPad, old monitors3:21.50Microsoft Surface, some laptops16:101.60MacBook, office monitors16:91.78TVs, most monitors19.5:92.17Phones21:92.33–2.39Ultrawide monitors32:93.56Super-ultrawide monitors

## Worked example

Inputs — I know: The resolution in pixels; Horizontal resolution (px): 2,560; Vertical resolution (px): 1,440; Diagonal screen size (optional): 27 in.

Results — **Screen ratio = 16:9**; Ratio as a decimal (width ÷ height) = 1.7778; Closest standard format = 16:9 – exact match; Written as x:9 = 16 :9; Written as x:10 = 17.78 :10; Pixel density = 108.8 PPI.

## Key terms

- **Screen ratio**: Width of the visible screen divided by its height.
- **Diagonal size**: Corner-to-corner length of the visible screen, the size in adverts.
- **PPI**: Pixels per inch along the diagonal; higher means sharper.

## FAQ

**What is the ratio of a 1920 × 1080 screen?**
16:9 (1.78:1).

**What ratio is an iPhone screen?**
2556 × 1179 reduces to 284:131, about 2.17:1 – marketed as 19.5:9.

**How do I find my screen's ratio?**
Look up the resolution in your display settings and enter it, or measure the visible width and height of the panel.

**Why can the screen ratio not be negative?**
It is a ratio of two lengths, which are always positive.

**What is the ratio of a 3440 × 1440 ultrawide?**
43:18 (2.39:1), sold as 21:9.

**What is the PPI of a 27-inch 1440p monitor?**
About 109 PPI; a 27-inch 4K monitor is about 163 PPI.


## Sources

- [Wikipedia – Display aspect ratio](https://en.wikipedia.org/wiki/Display_aspect_ratio)
- [Wikipedia – Display resolution](https://en.wikipedia.org/wiki/Display_resolution)
- [Wikipedia – Pixel density](https://en.wikipedia.org/wiki/Pixel_density)