Thread Pitch Calculator
Enter a measured diameter and pitch, get the metric and imperial sizes that actually fit.
Free tools
Screw and Bolt Identification Tools
Free calculators and reference charts for working out what a fastener is: thread pitch, metric and imperial sizes, wood screw gauges, head shapes and drive types. No sign-up, nothing to install.
Screw Size Chart
Every common metric and imperial thread size with pitch, tap drill and spanner size.
Metric to Imperial Screw Converter
Convert mm to inches, see the nearest fastener in each system, and which pairs are traps.
Wood Screw Gauge Chart
Gauge to millimetres, the metric size sold in its place, and the right pilot hole.
Screw Head and Drive Types
Head shapes by whether they sit flush, and how to tell the confusable drives apart.