PPI Calculator (Retina Display)

What Is PPI?

PPI stands for pixels per inch. It tells you how many pixels fit into one inch of a screen, measured in a straight line. The higher the number, the more pixels are packed into the same space, so text looks sharper, curves look smoother and individual pixels are harder to see.

Two screens can have the same resolution and still look very different. A 1920 x 1080 display on a 6-inch phone looks razor sharp, while the same resolution stretched across a 32-inch monitor looks soft. The pixel count is identical. The pixel density is not. That is exactly what this calculator measures.

How to Use the PPI Calculator

1. Pick a device or enter your own values. Choose a phone, tablet, laptop or monitor from the quick-start list, or leave it on custom.
2. Enter the resolution. Type the width and height in pixels, for example 2560 and 1600.
3. Enter the screen diagonal. Use the size from the spec sheet and select inches, centimeters or millimeters.
4. Choose a viewing distance (optional). Leave it on automatic and the tool picks a typical distance for that screen size.
5. Read your results. The numbers update as you type. Press Calculate to check for missing values, Copy result to save a summary, or Reset to start over.

The tool works entirely in your browser. Nothing you type is sent or stored anywhere.

What the Results Mean

• PPI: The main number. It is the pixel density of the screen.
• Density label: A plain-language rating from low density to ultra high density.
• Retina at this distance: Whether the pixels are too small for a person with normal vision to pick out at the selected viewing distance.
• Dot pitch: The distance between the centers of two neighboring pixels, in millimeters. Smaller means sharper.
• Pixels per square inch: The PPI value squared. It shows how many pixels cover one square inch of the panel.
• Screen size: The real width and height of the display area, calculated from the resolution and PPI.
• Aspect ratio: The shape of the screen, such as 16:9 or 3:2.
• Total and diagonal pixels: The full pixel count in megapixels, and the pixel length of the diagonal.

The PPI Formula

The calculation uses the Pythagorean theorem to find the diagonal in pixels, then divides by the physical diagonal in inches:

PPI = √(width² + height²) ÷ diagonal size in inches

Dot pitch follows directly from it:

Dot pitch (mm) = 25.4 ÷ PPI

Worked example

Take a 14.2-inch laptop with a 3024 x 1964 display.

1. Square each side: 3024² = 9,144,576 and 1964² = 3,857,296.
2. Add them: 13,001,872.
3. Take the square root: about 3,606 pixels along the diagonal.
4. Divide by 14.2 inches: about 254 PPI.

The dot pitch is 25.4 ÷ 254, or roughly 0.1 mm.

Is My Screen a Retina Display?

“Retina” is Apple’s marketing term, but the idea behind it is simple. Human vision can resolve detail down to about one arcminute (1/60 of a degree). If the pixels on a screen are smaller than that at your viewing distance, you can no longer see them individually.

That gives a handy rule of thumb:

Retina threshold (PPI) ≈ 3438 ÷ viewing distance in inches

The farther you sit, the fewer pixels per inch you need:

Viewing distance	Typical device	PPI needed
12 in (30 cm)	Phone	about 286
16 in (40 cm)	Tablet	about 215
20 in (50 cm)	Laptop	about 172
28 in (70 cm)	Desktop monitor	about 123

This is why a 27-inch 5K monitor at 218 PPI looks flawless on a desk, while a phone needs well over 300 PPI to give the same impression. It also explains why a 27-inch 4K monitor at about 163 PPI looks sharp from a normal desk distance but can show slightly soft text if you lean in close.

PPI Density Ranges

PPI range	Density	What to expect
Under 100	Low	Pixels are visible, common on older or very large screens
100 to 160	Standard	Fine for everyday desktop work, detail can look a little soft
160 to 220	High	Sharp text and images at most distances
220 to 300	Very high (HiDPI)	Very crisp, pixels are hard to see
300 and above	Ultra high	Typical of modern smartphones

PPI of Popular Screens

These values are calculated from each device’s published resolution and screen size, so you can compare them with your own result.

Screen	Resolution	Size	PPI
iPhone 16	2556 x 1179	6.1 in	about 461
iPad Pro 13 in (M4)	2752 x 2064	13 in	about 264
MacBook Pro 14 in	3024 x 1964	14.2 in	about 254
Studio Display / 27 in 5K	5120 x 2880	27 in	about 218
27 in 4K monitor	3840 x 2160	27 in	about 163
27 in QHD monitor	2560 x 1440	27 in	about 109
24 in Full HD monitor	1920 x 1080	24 in	about 92

PPI vs DPI: What Is the Difference?

The two terms are often mixed up, but they describe different things.

• PPI (pixels per inch) describes digital screens and image files. It is the number of pixels per inch of display.
• DPI (dots per inch) describes printers. It is the number of ink dots a printer places per inch of paper.

When you design for screens, think in PPI. When you prepare artwork for print, think in DPI. A photo does not become sharper just because you change a DPI setting. What matters is how many real pixels the image has and how large it is shown or printed.

Who Needs a PPI Calculator?

• Shoppers comparing laptops, monitors or phones can see beyond the resolution number and judge real sharpness.
• Web designers and developers can decide whether to serve 1x, 2x or 3x images and how to set up responsive layouts for high-density screens.
• Graphic designers and photographers can check how large an image can be displayed before pixels become visible.
• Gamers and video editors can pick the right monitor size for a given resolution and avoid paying for density they will not notice.
• Anyone with an unusual display, such as a projector, a TV used as a monitor or an e-reader, can find its pixel density in seconds.

Tips for Getting an Accurate Result

• Use the diagonal of the visible screen area, not the outer edge of the frame.
• Enter the native resolution of the panel, not a scaled or reduced setting in your operating system.
• For rotated screens, the order of width and height does not change the PPI, so either way works.
• If you only know the size in centimeters or millimeters, switch the unit instead of converting it by hand.

Frequently Asked Questions

What is a good PPI for a monitor?

For a desktop monitor viewed from about 24 to 30 inches away, 110 to 140 PPI is comfortable and 160 PPI or more looks very sharp. Above roughly 200 PPI the extra detail becomes hard to notice at that distance.

How do I find the PPI of my screen?

Enter the screen’s native resolution and its diagonal size into the calculator above. Both numbers are on the manufacturer’s spec sheet or the product page.

Does a higher PPI always mean a better screen?

No. Higher density means sharper detail, but screen quality also depends on brightness, contrast, color accuracy and refresh rate. Very high PPI can also cost more battery and graphics power, and some software does not scale well on it.

What PPI counts as a Retina display?

There is no single number, because it depends on viewing distance. The common rule is about 3438 divided by the distance in inches. That works out to roughly 286 PPI at phone distance and about 172 PPI at laptop distance.

Is 4K always sharper than 1080p?

Not on every screen size. A 4K display has four times as many pixels as Full HD, but the result depends on size. A 32-inch 4K monitor is about 138 PPI, while a 15.6-inch Full HD laptop is about 141 PPI, so the two are very close in sharpness.

Can I use this calculator for TVs and projectors?

Yes. Enter the resolution and the diagonal of the image area. For a projector, use the diagonal of the projected picture at your normal throw distance.

Does changing screen scaling change my PPI?

No. PPI is a physical property of the panel. Scaling in Windows, macOS or Android changes how large things appear, not how many physical pixels exist per inch.

Is my data saved?

No. The calculation runs in your browser and nothing you enter is uploaded or stored.

Final Thoughts

Resolution alone does not tell you how sharp a screen will look. Pixel density, combined with how far you sit from the display, is what really matters. Use the calculator above to check any phone, tablet, laptop, monitor or TV in seconds, and use the Retina check to see whether the extra pixels will actually be visible to you.