---
name: Density independent pixel
slug: density-independent-pixel
category: layout
status: published
created: 2026-08-21T00:00:00.000Z
modified: 2026-08-21T00:00:00.000Z
definition: A virtual unit of length that stays the same physical size across
  screen densities, so one number can describe a layout on every device.
aliases:
  - name: dp
    source: android
  - name: dip
    source: community
  - name: device independent pixel
    source: community
  - name: effective pixel
    source: fluent
tags:
  - platform-registers
  - screen-size
relations:
  contrastWith:
    - pixel-density
    - point-size
  variantOf: []
  partOf: []
  seeAlso: []
implementations: []
sources:
  - title: Support different pixel densities, Android Developers
    url: https://developer.android.com/training/multiscreen/screendensities
demo: inline
exhibit: false
useWhen: why sizes are written in dp, pt or CSS px
---

A density independent pixel is a unit of length that does not care how finely a screen is
made. Android anchors it to a reference display of 160 dots per inch, so one dp is one
physical pixel there and the conversion everywhere else is the ratio: at 3x, a 48 dp button
is painted with 144 device pixels and comes out exactly as large under the thumb.
[Pixel density](/pixel-density) is how many device pixels a screen packs into an inch; a dp
is the unit that cancels it out, so a control stays thumb sized on every phone that ships.
The pairing is the whole idea. One number describes the layout, and the platform does the
multiplication.

Every platform has this unit and each gave it a different name, which is most of the
confusion around it. Android says dp. Apple says point, which is not the
[typographic point](/point-size) despite sharing the word, and multiplies it by the device's
scale factor. Microsoft says effective pixel. The web says CSS pixel, anchored to roughly 96
per inch rather than 160, and exposes the multiplier as the device pixel ratio. The
arithmetic differs, the idea does not. Android adds one more unit, sp, which is a dp that
also scales with the reader's chosen text size, and it is the correct unit for anything made
of type.

The unit is a reference, not a physical measure, and that is worth being precise about. It
is calibrated to a typical viewing distance as much as to an inch, which is why a tablet
held at arm's length and a phone held close can share a number and still feel right, and why
a dp on a television is not a dp on a watch. What it reliably buys is that a
[viewport](/viewport) is measured in the same currency the layout is written in, so density
never moves a [breakpoint](/breakpoint) and a
[touch target](/touch-target-size) specified at 48 dp is 48 dp everywhere.

In practice the rule is that device pixels appear in exactly two conversations. The first is
raster assets, which need enough samples for the densest screen they will land on. The
second is hairlines, where a one dp rule is drawn with two or three device pixels and can
look heavier than intended, which is why some systems specify their dividers in device
pixels on purpose. Everything else, spacing, radii, target sizes, type, belongs in the
density independent unit, and a physical pixel value anywhere in a layout file is almost
always a bug waiting for a denser phone.