Convert Pixels per metre to Lines per inch

Convert Pixels per metre (px/m) to Lines per inch (lpi) instantly and accurately.

Conversion Formula

lpi = px/m × 0.0254

About Pixels per metre

The pixel per metre (px/m) is the SI-coherent form of image resolution. Because 1 inch = 0.0254 m exactly (international inch, 1959), 1 PPI = 1/0.0254 ≈ 39.37 px/m and 1 px/m = 0.0254 PPI. EXIF (IEC 61966-3) stores resolution as pixels per inch (ResolutionUnit = 2) or pixels per centimetre (ResolutionUnit = 3); px/m is used when normalising to SI for scientific or GIS workflows. Satellite remote-sensing GSD is often given in metres per pixel (the inverse); WorldView-3 at 0.31 m/px panchromatic ≈ 3.23 px/m. An A4 document scanned at 300 PPI ≈ 11,811 px/m. 1 px/m = 0.0254 PPI ≈ 0.00254 px/cm.

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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