Convert Pixels per foot to Lines per inch

Convert Pixels per foot (px/ft) to Lines per inch (lpi) instantly and accurately.

Conversion Formula

lpi = px/ft × 0.08333333333

About Pixels per foot

The pixel per foot (px/ft) is an imperial resolution unit used in architectural visualisation, large-format display engineering, and document scanning where distances are measured in feet. The foot is exactly 0.3048 m = 12 in (international foot, 1959), giving 1 px/ft = 1/12 PPI ≈ 0.08333 PPI. Microfilm scanners for engineering drawing digitisation (ANSI/AIIM MS23) are specified in px/ft; a 200 px/ft scan of a 24-inch D-size drawing yields 400 pixels across the 2-foot width. Outdoor LED walls at P6 pixel pitch (6 mm) covering one foot ≈ 50.8 px/ft. Building plans at 1:48 scale reduce 1 actual foot to 0.25 in on paper, requiring ≥ 3 px/ft for legibility. 1 px/ft = 1/12 PPI ≈ 0.083333 PPI ≈ 3.281 px/m.

About Lines per inch

The line per inch (lpi) is the standard unit of halftone screen frequency in offset, flexographic, gravure, and screen printing. Each halftone cell varies in dot size to simulate grey tones; a 150 lpi screen on a 1200 DPI printer allocates 1200/150 = 8 printer dots per cell row, giving an 8×8 = 64-level grey matrix. Industry benchmarks: newsprint 85-100 lpi; magazines 133-175 lpi; fine-art offset 175-200 lpi; screen printing (textiles) 35-65 lpi. Rule of thumb: required DPI ≥ 1.5 × lpi for acceptable AM halftone; ≥ 2 × lpi for high quality - so 150 lpi offset needs at least 300 DPI raster data. As a dimensional quantity, 1 lpi = 1 PPI = 1 DPI; lpi designates screen frequency in print. 1 lpi = 1 PPI = 2.54 lpcm.

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