How to use this calculator
Start with the deterministic fixture values already shown, then replace each input with measurements from your job. Use consistent units and review the highlighted assumptions before using the result in purchasing or production.
Formula and method
The base conversion is dots = mm ÷ 25.4 × DPI. Floor, nearest or ceiling creates an integer raster dimension; converting that integer back reveals actual size and error.
Worked example
At 300 DPI, 50 mm is 590.551 raw dots. Nearest rounding gives 591 dots and 50.038 mm actual size, an error of about +0.038 mm (+0.076%).
How to interpret the result
Nearest usually minimizes geometric error. Floor or ceiling may be useful where a layout must never exceed or fall below a boundary.
Limitations
Nominal DPI describes the raster. Mechanical tolerances, printhead alignment and media movement can still affect printed dimensions.
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