Convert Pixels per inch to Dots per centimetre

Convert Pixels per inch (PPI) to Dots per centimetre (dpcm) instantly and accurately.

Conversion Formula

dpcm = PPI × 0.3937007874

About Pixels per inch

The pixel per inch (PPI) is the universal standard for digital image resolution, defining how many pixels occupy one linear inch in a digital image, sensor, or display. Formally referenced in ISO 12232 (digital still cameras) and EXIF/TIFF (tags 0x011A/0x011B), PPI is both a capture parameter (scanner/sensor density) and a display characteristic. Display milestones: Macintosh 128K (1984): 72 PPI; Apple iPhone 4 Retina (2010): 326 PPI - above the human perceptual threshold at 25 cm; iPhone 15 Pro (2023): 460 PPI. Print benchmarks: 150 PPI (large-format, 1 m viewing); 300 PPI (standard offset, ISO 12647-2); 400-600 PPI (fine-art Giclée). EXIF stores PPI as unsigned RATIONAL; the historical default is 72/1, a carry-over from the original Macintosh screen standard. 1 PPI = 1/0.0254 px/m ≈ 39.37 px/m = 2.54 px/cm.

About Dots per centimetre

The dot per centimetre (dpcm) is the metric equivalent of DPI, defined as a CSS resolution unit in the W3C CSS Images Level 3 specification alongside dpi and dppx. A 96 DPI reference screen (CSS Media Queries Level 4 reference device) corresponds to 96/2.54 ≈ 37.795 dpcm. ITU-T T.4 (Group 3 facsimile, 1980) defines scan line density in metric units: standard resolution 3.85 lines/mm = 38.5 dpcm; fine resolution 7.7 lines/mm = 77 dpcm. ITU-T T.85 (JBIG compression) standardised these metric resolutions for cross-border interoperability. ISO 216 A4 scanned at 77 dpcm fine fax resolution yields 1617 pixels across page width. The CSS specification recommends dppx over dpcm for screen media queries, reserving dpcm for print stylesheets targeting metric-resolution printers. 1 dpcm = 2.54 DPI = 2.54 PPI exactly (since 1 in = 2.54 cm). 1 dpcm = 0.1 dot/mm.

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