Thread Pitch Chart (Metric & Unified)

Every standard size has one coarse pitch and one or more finer pitches. 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.