How to use this calculator
For a screen, enter pixel dimensions and physical diagonal. For a print, enter pixel dimensions and target pixels per inch. Choose inches or centimeters for physical measurements.
The math behind it
Screen PPI = √(pixel width² + pixel height²) ÷ diagonal in inches Print width (in) = pixel width ÷ PPI Print height (in) = pixel height ÷ PPI; 1 in = 2.54 cm
A worked example
A 1920 × 1080 screen with a 24-inch diagonal has about 91.787799 PPI. A 3000 × 2400 image printed at 300 PPI measures 10 × 8 inches.
Assumptions & precision
Square pixels and positive physical dimensions. Pixel dimensions must be whole numbers up to 1,000,000,000. PPI is image/display density; printer DPI counts ink dots and cannot be converted directly to PPI without a printing model. Switching screen/print mode resets the diagonal/PPI example. Changing physical units does not convert an entered diagonal. Unrounded intermediate values; results display up to 6 decimal places. Magnitudes above 10¹⁵ are rejected.
A common question
Does changing image DPI create detail?
No. Changing a resolution label changes the intended print size; it does not add original pixels or recover missing detail.