PPI & Screen Size Calculator
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TVThree quick reference calculators for display math: pixels per inch, recommended viewing distance, and aspect ratio simplification. Everything updates live as you type — nothing is sent anywhere.
PPI & Pixel Pitch Calculator
Pixels per inch from resolution and diagonal size.
diagonal_px = √(horizontal_px² + vertical_px²) · PPI = diagonal_px ÷ diagonal_inches · pixel pitch (mm) = 25.4 ÷ PPI
Viewing Distance Calculator
Rule-of-thumb distances for a given screen size and resolution.
"Cinematic" ≈ diagonal × 1.2 · "Comfortable" range ≈ diagonal × 1.6 to diagonal × 2.0 · "Pixel-invisible" distance uses the visual-acuity small-angle approximation: distance ≈ pixel_pitch ÷ tan(1 arcminute), where 1 arcminute (20/20 vision resolving limit) ≈ 0.0002909 radians. All three are commonly-cited rules of thumb (THX/SMPTE-style guidance), not physiological guarantees or a formal standard — actual comfortable distance varies by eyesight, content, and room.
Aspect Ratio Calculator
Simplify any width × height into its ratio.
Simplified via the Euclidean GCD algorithm: ratio = width÷gcd : height÷gcd. Non-integer inputs are scaled up to whole numbers first. "Common name" is the nearest standard ratio within a small tolerance, else "Custom".
Calculate pixel density, viewing distance and aspect ratio
These three display calculators answer different planning questions using values you enter. Pixels per inch describes resolution relative to screen size, viewing distance provides simple starting estimates, and aspect ratio simplifies a width and height. The page does not detect your display’s dimensions or measure your eyesight. Use verified specifications and consistent units, then compare the outputs with how you actually use the screen.
How to use the tool
- For PPI, enter horizontal pixels, vertical pixels and the visible screen diagonal in inches. Use the panel’s native resolution when comparing physical pixel density between displays.
- For viewing distance, enter the diagonal size and select a resolution preset from 720p through 8K. Choose Custom to enter dimensions that are not in the preset list.
- For aspect ratio, enter width and height in matching units. Pixels, centimeters or inches work for the ratio provided both dimensions use the same unit.
- Read the outputs after each edit. Keep size fixed when comparing resolution, and keep resolution fixed when comparing size, so you can see which input drives the result.
Read PPI and pixel pitch
The calculator first finds the diagonal pixel count using the square root of horizontal pixels squared plus vertical pixels squared. Dividing that count by diagonal inches gives PPI. Pixel pitch is 25.4 divided by PPI, expressed in millimeters. Higher PPI means smaller pixel spacing when the inputs describe the panel’s physical geometry.
For example, a 27-inch 2560 × 1440 display is about 108.8 PPI with a pitch near 0.2335 mm. A 27-inch 3840 × 2160 display is about 163.2 PPI with a pitch near 0.1557 mm. Both occupy a similar desk area, but the second has denser pixels. OS scaling can keep text comfortably sized while using that density.
Browser DPR is not interchangeable with PPI. DPR describes a rendering scale between CSS and device pixels, while PPI also requires a physical inch measurement. Entering browser logical dimensions into the PPI calculator can understate density on a scaled display. Use the resolution checker to understand browser values, then verify the manufacturer’s panel specification.
Treat viewing distances as starting points
The cinematic estimate is diagonal multiplied by 1.2. The comfortable range is diagonal multiplied by 1.6 through 2.0. These are simple size-based heuristics used by this page; they are not formal certification or a personalized ergonomic recommendation. They do not account for your desk depth, posture, task, text size or field of view.
For a 55-inch display, those formulas yield roughly 5 feet 6 inches for the cinematic estimate and about 7 feet 4 inches to 9 feet 2 inches for the comfortable range. Changing resolution alone does not change these two results, because their formulas only use diagonal size.
The pixel-invisible estimate does use resolution. It divides calculated pixel pitch by the tangent of one arcminute, using a simplified visual-acuity assumption. It is a geometric estimate of pixel visibility, not a guarantee that pixels disappear for everyone or that detail becomes impossible to appreciate closer up. Contrast, content and individual vision matter.
Understand simplified and named ratios
A 1920 × 1080 input reduces to 16:9 and has a decimal ratio of approximately 1.78:1. A 3440 × 1440 input reduces to 43:18, about 2.39:1. A marketing label such as ultrawide does not replace that exact arithmetic, and a common name appears only when the decimal is close enough to a listed reference.
Decimal inputs are scaled to a fixed precision before the greatest-common-divisor calculation. Extremely fine fractional differences may therefore be rounded. For a file or layout with a very specific ratio, retain its original dimensions alongside the simplified output. Use the frame-shape player to see how fitting one source into another ratio changes cropping.
Frequently asked questions
Is higher PPI always better?
Higher density can make pixels less conspicuous, but useful text size also depends on scaling and viewing distance. Compare density alongside screen size, resolution and the work you do.
Should I use native or scaled resolution for PPI?
Use native panel pixels for physical density. A scaled desktop workspace describes software layout and does not change how many physical pixels fit into an inch.
Does the viewing calculator tell me where I must sit?
No. It offers formula-based starting distances. Adjust for comfort, readable text, room layout and the content you use rather than treating one number as a requirement.
Why does distance stay the same after I change resolution?
The cinematic and comfortable formulas depend only on diagonal size. The pixel-visibility estimate changes with calculated pitch, so resolution affects that output.
Can width and height use different units?
Convert them to the same unit first. A ratio between centimeters and inches without conversion gives an incorrect shape, even though the calculator can still divide the numbers.
References: MDN: rendering scale and DPR.
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