Convert Dots per point to Dots per inch

Convert Dots per point (dot/pt) to Dots per inch (DPI) instantly and accurately.

Conversion Formula

DPI = dot/pt × 72

About Dots per point

The dot per point (dot/pt) expresses output resolution relative to the PostScript point - exactly 1/72 inch, codified by Adobe in the PostScript Language Reference (1985). The Apple Macintosh 128K (1984) ran its built-in CRT at exactly 72 DPI, placing 1 dot per point - an intentional WYSIWYG design: a 12-point character on screen measured 12 pixels tall and printed at 12 points on the Apple LaserWriter. Device resolution milestones: Apple LaserWriter (1985) 300 DPI = 300/72 ≈ 4.17 dot/pt; HP LaserJet 4 (1992) 600 DPI ≈ 8.33 dot/pt; Linotronic 300 imagesetter (1985) 1270 DPI ≈ 17.64 dot/pt; Agfa Selectset 5000 at 2400 DPI = 33.33 dot/pt. TrueType and OpenType font hinting instructions align outline points to raster device pixels at the current dot/pt ratio. The CSS pt unit equals the PostScript point: 1 CSS pt = 1/72 CSS in = 4/3 CSS px at 1 dppx. 1 dot/pt = 72 DPI = 72 PPI.

About Dots per inch

The dot per inch (DPI) is the standard resolution metric for printed output, specifying how many individual ink or toner dots a printing device places per linear inch. Unlike a pixel, a printed dot is a physical deposit of ink variable in size and subject to dot gain (ink spread into substrate). Inkjet photo printers: Epson SureColor SC-P900 up to 5760 DPI; HP DesignJet Z9+Pro at 2400 DPI. Laser printers: HP LaserJet standard 600 DPI; enterprise class 1200 DPI. Offset CTP plate imaging: 2400-3600 DPI. Rule of thumb: required DPI ≥ 1.5 × LPI for acceptable halftone; ≥ 2 × LPI for high quality - a 175 lpi magazine job needs ≥ 350 DPI raster data. Thermal dye-sublimation printers achieve continuous-tone output at 300 DPI because dye diffuses to fill each cell. As a dimensional unit, 1 DPI = 1 PPI; DPI implies physical print output. 1 DPI = 2.54 dots/cm = 25.4 dots/mm.

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