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Printable 1:1 gauge

Screw / bolt shaft gauge (metric)

Actual-size openings for common metric major diameters. Avoid dragging sharp threads on screens — paper gauges are safer for rough checks.

Back to screw size checker

Calibration square (50 mm)

After printing, measure this square with a ruler. If it is not 50 mm, your printer scaled the page — reprint at 100% / Actual size.

50 mm verify with ruler

Gauge openings

Circles are drawn in real millimeters. Hold the object over the matching opening.

M2 M2.5 M3 M4 M5 M6 M8 M10 M12 ExactSize Tools · print at 100%
ExactSize Tools · Physical size reference only · Not a substitute for a calibrated metal gauge when precision is critical.