DPI and PPI Calculator
Calculate pixel density, print resolution and the maximum print size for an image.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
PPI describes image pixels per inch; DPI describes printer dots, and the terms are not interchangeable. 300 PPI is a common reference for some close-viewed prints, not a universal quality threshold. Estimated print dimensions depend on target PPI; perceived sharpness also depends on viewing distance, printer, and image.
Worked example
calculated with the default values below
Image width 4,000 px · Image height 6,000 px · Screen diagonal (for PPI) 27 in · Screen width 5,120 px · Screen height 2,880 px · Target print resolution 300 ppi Screen pixel density 217.6 ppi · Image megapixels 24.0 MP · Maximum print width at target PPI 13.33 in · Maximum print height at target PPI 20.00 in · Maximum print width 33.9 cm · Print quality note Print dimensions are estimates; perceived sharpness depends on viewing distance, printer, and image.
General background references
Disclaimer
These calculators give general estimates. Sizing, pricing, availability and standards vary by brand, retailer and country, so treat the output as a starting point and confirm it against the seller's or authority's own figures.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
PPI = √(w² + h²) ÷ D; MP = w × h ÷ 1000000
- w
- horizontal pixels
- h
- vertical pixels
- D
- screen diagonal, inches
- PPI
- pixels per inch
- MP
- megapixels
Print size at the target ppi is w÷PPI_t by h÷PPI_t inches (×2.54 for cm); the quality note follows MP bands 6/12/20.
Frequently asked questions
What should I know about this estimate?
PPI describes image pixels per inch; DPI describes printer dots, and the terms are not interchangeable. 300 PPI is a common reference for some close-viewed prints, not a universal quality threshold. Estimated print dimensions depend on target PPI; perceived sharpness also depends on viewing distance, printer, and image.