Identify external and internal threads by entering your measurements — instantly matched against metric, imperial, and specialty thread standards.

Units
Thread Type
Major Diameter (mm)
mm
Pitch (mm)
mm
Threads per Inch (TPI)
TPI
Tolerance ±5%
  1. 1
    Select units

    Choose mm or Inch depending on how you are measuring.

  2. 2
    Select thread type

    Use External for bolts/studs, Internal for nuts/tapped holes.

  3. 3
    Measure the diameter

    For external threads, measure the outer (major) diameter with calipers. For internal threads, measure the minor (inner) diameter of the bore.

  4. 4
    Measure the pitch or TPI

    Use a thread pitch gauge or count the number of thread crests over 25.4 mm (1 inch) to find TPI. Alternatively enter the pitch directly in mm or inches.

  5. 5
    Tap Identify Thread

    Results are ranked by match quality. Excellent Good Acceptable Poor

Reference aid only. Always verify critical dimensions directly against the relevant published standard, and use calibrated measurement instruments. Do not solely rely on this website where incorrect thread identification could cause injury, death, or property damage.