Worked example
For a 150 LPI screen and a 2× sampling factor, the image target is 300 PPI. An 8 × 10 in print therefore needs 2,400 × 3,000 pixels, or 7.2 megapixels.
Ask for LPI, not the printer’s DPI
LPI describes the halftone line screen. PPI describes image pixels, while printer DPI describes output dots. A printer’s advertised 1,200 DPI does not mean the photograph needs 1,200 PPI. Use the line ruling for the actual press, paper and job.
Choose the sampling factor with your printer
Adobe gives 1.5 to 2 times the screen frequency as a general image-resolution range for halftone work. The example uses 2; it is an editable assumption, not a universal requirement. A print provider may specify something different for the artwork or screening method.
Measure the final image area
Enter the image’s printed dimensions after layout scaling. The calculator does not add bleed or create pixels in a source file. If your image is too small, resampling can change its pixel count but cannot recreate missing photographic detail. Non-halftone workflows may use different preparation rules.
Explore the related calculation
For a different starting point, try the print bleed calculator or return to the main calculator. Browse the complete tool directory for this site.
Reference and corrections
The definitions and assumptions above follow these sources; the examples and calculator arithmetic are original to this page.
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