Thread Pitch Chart (Metric & Unified)

Every standard size has one coarse pitch and one or more finer pitches. The thread pitch calculator path explains pitch-to-TPI conversion and routes pitch searches to the chart, tap-drill, tapping-feed and three-wire measurement tools. Coarse threads (metric coarse, UNC) cut deeper per turn, strip less easily in soft material and tolerate damage and dirt — they are the sensible default. Fine threads (metric fine, UNF) advance less per revolution, giving finer adjustment, more thread engagement in thin walls and a higher stress area, at the cost of easier cross-threading. Metric pitch is named directly in millimetres (M8×1.25 is a 1.25 mm pitch), while Unified sizes are named by their thread count per inch (1/4-20 means 20 TPI); the two columns let you compare either way.