Convert Dots per pixel to Pixels per centimetre

Convert Dots per pixel (dppx) to Pixels per centimetre (px/cm) instantly and accurately.

Conversion Formula

px/cm = dppx × 37.79527559

About Dots per pixel

The dot per CSS-pixel unit (dppx, or the x descriptor in CSS) is defined in W3C CSS Images Level 3 / Media Queries Level 4 as the ratio of physical device pixels to CSS reference pixels, where the CSS spec fixes 1 CSS inch ≡ 96 CSS px exactly. Therefore 1 dppx = 96 DPI = 96 PPI exactly; a screen reporting device pixel ratio (DPR) of 2 has 2 dppx = 192 physical dots per CSS inch. JavaScript exposes DPR as window.devicePixelRatio, numerically equal to dppx. Reference values: standard laptop (96-110 PPI): 1 dppx; MacBook Pro 13-inch Retina (227 PPI): 2 dppx; iPhone 15 Pro 6.1-inch (460 PPI): 3 dppx; Samsung Galaxy S24 Ultra (501 PPI): ≈ 3.09 dppx. The HTML img srcset x descriptor (photo@2x.jpg 2x) is numerically equal to dppx, serving higher-resolution images for HiDPI screens. The CSS @media (min-resolution: 2dppx) query targets any display with DPR ≥ 2. 1 dppx = 96 DPI = 96 PPI.

About Pixels per centimetre

The pixel per centimetre (px/cm) is the metric counterpart of PPI, measuring pixel density per centimetre. EXIF assigns ResolutionUnit = 3 when resolution is stored in px/cm; Canon, Fujifilm, and Nikon cameras can output EXIF data in px/cm. GIMP stores and displays image resolution in px/cm in its XCF format and Image Properties dialog. DICOM (NEMA PS 3.3) stores spatial resolution as PixelSpacing in mm/pixel; a radiograph at 0.2 mm/px = 5 px/mm = 50 px/cm = 127 PPI. At 10×15 cm print size, a 12 MP image (4000×3000 px) prints at 4000/15 ≈ 266.7 px/cm ≈ 677 PPI - well above the ISO 12647-2 minimum of ≈ 118 px/cm (300 PPI). Since 1 inch = 2.54 cm exactly, 1 px/cm = 2.54 PPI exactly. 1 px/cm = 2.54 PPI = 10 px/dm = 100 px/m.

Quick Reference Table

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