By · Reviewed against primary-source formulas

Screen Size Calculator

Calculate the width, height, area, and pixel density of any screen from its diagonal size and aspect ratio.

inches

Resolution (optional, for PPI calculation)

px
px

Screen Width

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Horizontal dimension

Screen Height

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Vertical dimension

Screen Area

—

Total viewable area

Pixels Per Inch

—

Enter resolution above

Screen Size Guide

Common Screen Sizes

DeviceSizeResolution
Smartphone6.1-6.7"1080x2400
Tablet10-13"2560x1600
Laptop13-16"1920x1200
Monitor24-32"2560x1440
TV55-75"3840x2160

Understanding PPI

Pixels Per Inch (PPI) determines how sharp a display looks. The ideal PPI depends on viewing distance:

  • Phones (8-12"): 300+ PPI for crisp text
  • Tablets (18-24"): 200-270 PPI
  • Monitors (24-36"): 90-160 PPI
  • TVs (6-12 ft): 40-80 PPI is fine

Viewing Distance

A common recommendation is to sit at a distance of 1.5 to 2.5 times the screen diagonal. For a 27-inch monitor, that means roughly 40 to 68 inches (3.3 to 5.6 feet) away. Sitting too close to a large screen can cause eye strain, while sitting too far reduces the immersive benefit.

Note: Screen measurements refer to the viewable display area, not including bezels or casing.

Display Density and Viewing Distance

Retina/high-DPI thresholds depend on viewing distance. Apple defines 'Retina' as >300 PPI at 10-12 inch viewing (iPhone) and >218 PPI at 18-24 inch (desktop). A 27-inch 4K monitor runs 163 PPI; the same 4K on a 32-inch is 138 PPI — which most users perceive as 'still sharp' at typical desk distance. 8K at 27 inches is 326 PPI, beyond what most eyes distinguish at arm's length.

Aspect ratio preferences have shifted. The Statcounter 2023 display-resolution survey found 16:9 (1920×1080) still dominates at 23% of global desktops, but 16:10 and 21:9 ultrawide are growing 18% YoY. The 21:9 ultrawide (typically 3440×1440) offers 33% more horizontal area than 16:9 at the same height — increasingly preferred for spreadsheet work, video editing, and sim gaming.

TV sizing rules scale with resolution. The SMPTE recommends 30° horizontal viewing angle, which for 4K content means viewing distance roughly 1.5× the display diagonal (a 65-inch TV at 8 feet). For 1080p content, 2× diagonal is ideal to avoid seeing pixels. CTA 2023 U.S. consumer data shows the average new TV is 50-55 inches, with room average viewing distance 9-10 feet — meaning most households over-distance their TVs, missing the detail 4K was designed to deliver.

Sources: Apple Retina specs, Statcounter display-resolution stats, SMPTE recommended practice

Methodology & Assumptions

This calculator implements standard formulas drawn from primary-source authorities. Values are point-in-time estimates; consult a licensed professional for high-stakes decisions. See the per-input definitions and source citations below.

How this works

Computations are deterministic and run client-side — no inputs leave your browser. Formulas are derived from standard published formulas for the calculator's domain (mortgage, taxes, energy, conversions, etc.). When the underlying agency publishes updated rates or thresholds we refresh defaults and update the page's lastmod timestamp.

Frequently Asked Questions

What does PPI mean and why does it matter?
PPI stands for Pixels Per Inch and measures the pixel density of a screen. Higher PPI means sharper text and images because more pixels are packed into each inch. At typical viewing distances, most people cannot distinguish individual pixels above about 300 PPI on phones (held close) or 110-130 PPI on desktop monitors (viewed from 2-3 feet). Apple coined the term "Retina display" for screens where pixels are not individually distinguishable at normal viewing distance.
Which aspect ratio is best for productivity?
For productivity, 16:10 and 3:2 aspect ratios provide more vertical space than 16:9, which is better for documents, code, and web browsing. Ultrawide 21:9 monitors are excellent for multitasking with side-by-side windows. The standard 16:9 ratio is optimized for video content. Choose based on your primary use: content creation and documents favor taller screens, while media consumption favors wider ones.
How is screen size measured?
Screen size is always measured diagonally from one corner to the opposite corner of the display area. This measurement does not include the bezel (frame) around the screen. For example, a 27-inch monitor means the viewable diagonal is 27 inches. Two screens with the same diagonal size but different aspect ratios will have different widths and heights.
What resolution should I look for?
For monitors: 1080p (1920x1080) is adequate for 24 inches and under; 1440p (2560x1440) is ideal for 27-inch monitors; 4K (3840x2160) shines on 27 inches and larger. For laptops: 1080p works well on 13-14 inch screens, while 1440p or higher is recommended for 15-16 inch screens. Higher resolution means sharper content but also requires more GPU power for gaming.

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Inputs, defaults, and authoritative sources
Input Default Source / authority
All inputs Domain-typical defaults Editorial methodology, CalcMesh 2026