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Screen PPI Calculator

Unit Converters

Pixel density, dot pitch and Retina viewing distance

Quick Answer

Screen PPI Calculator: Pixel density, dot pitch and Retina viewing distance. Dot pitch = 25.4 ÷ PPI (mm).

PPI163.2px/in
Total pixels8.29MP
Dot pitch0.156mm
Retina distance54cm
Sharpness ratingSharp

Calculation steps

  1. 1Diagonal pixels: √(3840² + 2160²) = 4,406 px
  2. 2PPI = 4,406 ÷ 27″ = 163.2
  3. 3Dot pitch = 25.4 ÷ 163.2 = 0.156 mm

PPI tiers

PPIPerception
< 100Grainy — old monitors / TVs at distance
100–140OK — mainstream office monitors
140–200Sharp — HiDPI laptops
200–300Very sharp — 4K monitors / tablets
≥ 300Retina class — flagship phones
PPI = diagonal pixels ÷ diagonal inches. At the Retina distance (one pixel subtends 1 arcminute) the eye can no longer resolve individual pixels — phones are held close (~25cm) so they need 300+ PPI, while monitors viewed at 60cm+ are fine at 140.

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How to Use

  1. Pick units: switch source and target units in the Screen PPI Calculator.
  2. Enter a value: results sync both ways instantly — no convert button needed.
  3. Use the reference table: common conversions are listed for instant lookup.
  4. Copy the result: copy the converted value with its unit.

Key Points

  • Screen PPI Calculator is a free online unit conversion tool — open and use, no sign-up.
  • All calculations run locally in your browser; your data never leaves the device.
  • Key capability: Pixel density, dot pitch and Retina viewing distance.
  • Results come with formulas and reference tables so you can verify every number.

Formula & How It Works

Pixel density

PPI = √(width² + height² px) ÷ diagonal inches

Dot pitch = 25.4 ÷ PPI (mm)
Reference: iPhone ≈ 460, 27" 4K ≈ 163, 27" 1440p ≈ 109, 24" 1080p ≈ 92

FAQ

How do I use the Screen PPI Calculator?
Open the page and fill in the input fields — results update automatically. Pixel density, dot pitch and Retina viewing distance.
Are the results accurate?
Yes. Standard formulas and conversion factors are used and verified.
Is it free? Do I need to sign up?
Completely free. No registration, login or download required.
Does it work on mobile?
Yes. The responsive design works on phones, tablets and desktops.
Is my data saved?
No. Everything runs locally in your browser.

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Source & Updates

Based on SI conversion factors and international standards. Last updated: 2025-07

Authoritative sources:

Last updated:

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Maintained and periodically reviewed by the YiJianSuan editorial team — review process in ourEditorial Policy.

Cite this page: YiJianSuan. Screen PPI Calculator[EB/OL]. https://www.yijiansuan.com/en/c/convert/ppi

Results provided by this tool are for reference only and do not constitute professional advice.