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Phones, apps & storage

Screen DPI Calculator

Give it a resolution and a diagonal and this returns the pixel density, the Android density bucket the device falls into, the screen size in density-independent pixels, and the distance at which the pixels stop being resolvable. The last one is the number that decides whether more pixels would be worth anything.

in
in

Phone ~12in, tablet ~16in, laptop ~24in, TV ~90in.

— pixels per inch

Android density buckets, and where this screen sits.
Bucket Nominal dpi Scale factor Range Typical devices

How density is calculated

diagonal pixels = √(width² + height²) ppi = diagonal pixels ÷ diagonal inches dp = pixels ÷ (ppi ÷ 160) retina distance = 3438 ÷ ppi inches (one arcminute of visual angle)

A 1440 × 3120 display on a 6.8-inch diagonal works out to 3,436 diagonal pixels over 6.8 inches, or 505 ppi. Android puts that in the xxxhdpi bucket and scales every layout by 4× from the 160 dpi baseline.

What dp means and why it exists

A density-independent pixel is a pixel on a 160 dpi screen. Android layouts are written in dp so a 48 dp button is the same physical size on every device — about 0.3 inches, which is roughly the size of a fingertip. On a 505 ppi phone, that 48 dp button is 151 real pixels. On a 160 dpi tablet it is 48. The developer writes one number; the system does the multiplication.

This is why a phone with a huge resolution does not fit more content on screen than a cheaper one of the same physical size. Both are around 411 dp wide, and the layout is identical — the expensive one just draws it with more pixels.

The point where more pixels stop mattering

Human visual acuity resolves about one arcminute of angle, which puts the useful limit at roughly 3438 ÷ viewing distance in inches ppi. At a normal phone distance of 12 inches that is about 286 ppi. Every flagship phone has been past that for a decade, which is why resolution stopped being a meaningful spec and refresh rate, brightness and colour took over as the things that actually differ.

Where it still matters. Headsets, where the display sits an inch from the eye and needs thousands of ppi to look solid, and text rendering at small sizes, where extra density genuinely improves legibility even past the acuity limit.

Questions people ask about this

What is a good PPI for a phone?

Anything above about 300 ppi is beyond what the eye resolves at normal holding distance, so 400 to 500 ppi — where most modern phones sit — is comfortably sharp. Past that, extra density affects battery life and rendering cost rather than anything you can see.

How do I convert pixels to dp?

Divide pixels by the density scale factor, which is ppi ÷ 160. On a 480 dpi screen the factor is 3, so 144 pixels is 48 dp. The reverse — dp to pixels — multiplies instead. Android rounds each device to the nearest bucket (160, 240, 320, 480, 640) rather than using the exact measured ppi.

What are Android density buckets?

Six standard density classes — ldpi 120, mdpi 160, hdpi 240, xhdpi 320, xxhdpi 480 and xxxhdpi 640 — that Android sorts every device into so developers can supply one set of assets per class rather than one per device. mdpi at 160 dpi is the baseline where 1 dp equals 1 pixel.

Does higher resolution mean a better screen?

Past roughly 300 ppi at phone distance, no. Two phones at 400 and 500 ppi look identical to the eye, and the higher one costs more battery to drive. Refresh rate, peak brightness, colour accuracy and panel type make far more visible difference than resolution does above the acuity limit.

Where these numbers come from

Rates on this page were last checked against the published price lists on . Grading companies change fees and pause tiers without notice — confirm the total on the submission form before you pay.