PPI Calculator

Pixel density from resolution and screen size.

Pixel density from resolution and screen size. PPI is a property of a display or of an image at a stated size.

Written and maintained by Mohit PatelLast checked August 4, 2026How we build these

Screen width in pixels

Screen height in pixels

Screen diagonal

Pixel density

109 PPI

pixels visible up close

Diagonal in pixels2,937

Physical width23.53 in

Physical height13.24 in

Pixel density109 PPI

PPI is a property of a display or an image at a stated size; DPI is a property of a printer. A 27-inch monitor at this resolution shows roughly 109 pixels per inch, which is why the same design looks different on a phone.

How the PPI Calculator works

PPI is a property of a display or of an image at a stated size. The same design looks different on a phone and a monitor because the pixel density differs by a factor of two or more, not because anything about the file changed.

Also known as: pixels per inch calculator · screen pixel density · PPI vs DPI calculator

Pixel density on a screen

PPI is pixels per inch on a display, calculated from the diagonal resolution divided by the diagonal size in inches. The diagonal in pixels comes from the width and height by Pythagoras.

A 27 inch monitor at 2560 by 1440 has a diagonal of 2937 pixels across 27 inches, which is 109 PPI. A 15.6 inch laptop at the same resolution is 188 PPI, and the difference is visible immediately.

The figure describes how densely packed the pixels are, which combined with viewing distance determines whether individual pixels are distinguishable. It is not a quality measure on its own, since a high density panel with poor colour is still a poor panel.

What counts as high density

Above roughly 200 PPI, pixels become hard to distinguish at typical viewing distances, which is where the various marketing terms for high-density displays sit.

Phones commonly exceed 400 PPI, partly because they are held close and partly because the specification is a selling point. Tablets sit around 260 to 320. Desktop monitors are typically 90 to 160, since they are viewed from further away.

Viewing distance is the variable that makes a single threshold meaningless. A television at 40 PPI viewed from three metres looks as sharp as a phone at 400 PPI held at 30 centimetres, because the angular resolution is what the eye responds to.

CSS pixels and device pixels

Web design works in CSS pixels, which are a unit of measurement rather than a physical pixel. A high-density display renders multiple device pixels per CSS pixel, which is why a phone reporting 390 CSS pixels wide may have 1170 physical ones.

The ratio is the device pixel ratio, commonly 2 or 3 on modern phones. It is what makes text look sharp on a phone despite the layout using the same numbers as a desktop.

For images the consequence is direct: an image displayed at 400 CSS pixels wide on a device pixel ratio of 2 needs to be 800 actual pixels to look sharp. Serving the 400 pixel version produces a visibly soft image on most phones, which is why responsive image markup exists.

Serving images at the right size

The srcset attribute lets a browser choose between several versions of an image based on the display and the layout, which handles pixel density without sending everyone the largest file.

The trade is bandwidth against sharpness. A 3x image on a 3x display looks perfect and is nine times the pixels of the 1x version, which on a mobile connection is a real cost.

In practice 2x is the usual compromise, since the difference between 2x and 3x is difficult to see on most content while the file size difference is substantial. Photographs tolerate more compression at higher density too, which makes a heavily compressed 2x image often better than a lightly compressed 1x one at the same file size.

Where PPI is used to mean the other thing

PPI and DPI are used interchangeably in most conversations, and the distinction only matters occasionally. Strictly, PPI describes pixels in an image or on a display, and DPI describes ink dots a printer lays down.

The place it causes real confusion is image metadata, where the field is labelled DPI and describes an intended print resolution in pixels per inch, which is PPI by the strict definition.

For practical purposes the useful discipline is to talk about pixel dimensions and physical size rather than either acronym. Saying an image is 3000 by 2000 pixels and will print at 10 by 6.7 inches removes all ambiguity, where saying it is 300 DPI does not.

Where to go next

The PPI question rarely arrives on its own. These are the ones that usually come with it:

DPI Calculator — Effective resolution at your print size.
Pixels to Inches Calculator — Physical size depends on the resolution you choose.
Aspect Ratio Calculator — The resize is fine; the composition is not.
Etsy Fee Calculator — Every Etsy fee on one sale, itemised.

Not financial advice. Marketplace fees change, and they vary by country, plan and seller status. Every rate here is an editable default, not a quoted price, check the platform's current fee schedule before you price a product against it. This is not tax or business advice.

Frequently asked questions

How is PPI calculated?

The diagonal in pixels, found from width and height by Pythagoras, divided by the diagonal in inches.

What PPI counts as high density?

Above roughly 200 PPI, individual pixels become hard to distinguish at normal viewing distance. Phones commonly exceed 400; desktop monitors often sit near 110.

Does PPI matter for web design?

Indirectly. Browsers work in CSS pixels rather than device pixels, and high-density displays render multiple device pixels per CSS pixel, which is why images need to be supplied at 2× for them to look sharp.

Is PPI the same as resolution?

No. Resolution is the total pixel count; PPI is how densely those pixels are packed. A 4K phone and a 4K television have the same resolution and vastly different PPI.