How to use
Enter the horizontal and vertical pixel counts of the active display area, then its physical diagonal in inches or centimeters. Calculate to see pixels per inch (PPI), the distance between neighboring pixel centers and the physical width and height. Use the panel’s native resolution and active diagonal, excluding the bezel.
This is useful when comparing displays with different resolutions and sizes. It assumes a rectangular panel with square, evenly spaced pixels. It does not use CSS pixels, devicePixelRatio, browser zoom or operating-system scaling as a substitute for physical measurements.
The pale examples calculate without editing. Focusing any numeric field clears all examples together; later edits keep your own values. The compact diagram stays visible when values are missing or invalid. Dimension labels update with valid values; a dash means the dimension is not yet available.
Geometry behind the result
The diagonal pixel count is √(width² + height²). Divide it by diagonal inches to obtain PPI. Physical width in inches is horizontal pixels / PPI; height follows the same rule. Pixel pitch in millimeters is 25.4 / PPI. One inch is exactly 2.54 cm.
The outline preserves the width-to-height ratio and its diagonal connects opposite corners. The separate grid magnifies a few conceptual pixels. Each grid cell represents one square pixel; the label reports its calculated pitch. Neither drawing is calibrated to the physical size of your screen.
Two examples
A 1920 × 1080 display with a 24-inch diagonal has about 91.79 PPI, 0.28 mm pitch and dimensions of 20.92 × 11.77 inches. Entering 60.96 cm for the same diagonal gives the same answer.
A 3840 × 2160 display at 27 inches gives about 163.18 PPI and 0.16 mm pitch. Its dimensions are about 23.53 × 13.24 inches. Higher PPI means smaller pixel spacing, but perceived sharpness also depends on viewing distance and content.
Reading and using the output
Pixel counts must be whole positive numbers; diagonal length must be positive. Inputs are capped at one billion. Use a decimal point or comma without grouping. Zero, negative values, missing dimensions and non-finite values are rejected.
The displayed measurements round to at most two decimals without changing internal calculations. Values smaller than 0.01 are shown with a less-than sign. Copy result includes density, pitch, physical dimensions and diagonal. Editing any input or selection invalidates the result; calculate again before copying. Clear empties numeric inputs while keeping the unit.
Is PPI the same as resolution?
No. Resolution counts pixels along each side; PPI also depends on physical size. Two panels with the same resolution may have different density.
Should I enter inches or centimeters?
Either is supported. Use the actual diagonal and the matching unit. For example, 24 inches equals 60.96 centimeters. Changing the selector does not convert the typed number automatically.
Does the grid show subpixels?
No. It illustrates whole square pixels, not RGB subpixel layouts, panel technology or manufacturing gaps.
Can this predict print quality?
No. This page calculates a display’s density from resolution and physical diagonal. Planning an image’s printed dimensions is a separate calculation.