Enter a specification
- Choose the thread family. Use the form called out on the drawing. The family guides explain their designation formats.
- Select a size or enter a diameter and pitch. Inch specifications commonly use threads per inch (TPI); metric specifications use the distance between adjacent threads. Pipe sizes, BA numbers and Pg codes are catalog designations, not measured diameters.
- Set the fit and any other specified options. Check both external and internal selections, and include starts, hand and engagement where applicable.
- Choose result units. Switching between inches and millimetres converts the results while keeping the same thread specification.
Some families have a fixed size list. If custom inputs are unavailable, select a listed size rather than substituting the nearest measured diameter.
Read the results
| Label | Meaning |
|---|---|
| Minimum / maximum | The lower and upper dimensional limits for the selected thread and fit. |
| Mean | The midpoint between two limits. It is a reference value, not a separate manufacturing requirement. |
| Tolerance | The difference between the upper and lower limits. |
| ref | A reference dimension. It does not establish a controlled limit on that side of the interval. |
| — | The selected specification does not define that result. |
Major diameter is the largest diameter of the thread profile; minor diameter is the smallest. The crests are at the major diameter on an external thread and at the minor diameter on an internal thread.
Each result states its reference standard or catalog. Match that basis to the drawing. Converted values can show additional decimal places; those digits do not add precision to the original rounded limits.
Wires, drills and coatings
- Measuring wires
- Check the selected wire diameter and the measurement limits together. The wire method and measurement datum are shown with the results; taper-thread measurements depend on their stated position.
- Tap drills
- Select cut or form tapping where offered, then set the thread percentage if it is adjustable. The drill list shows nearby sizes relative to the target. Toolmaker recommendations, material and process conditions still determine the final drill choice.
- Coating and polishing
- Enter the thickness range and choose the external or internal thread. Compare the finished limits with the limits needed before treatment. Optional finished-limit overrides apply to that selected side.
- Pipe lengths
- Read length names and datums before using their values. A hand-tight engagement length and a dimension at a gauge plane describe different parts of the connection.
Save and share
Projects are stored in this browser. Download a JSON backup to move them to another device or keep a copy before clearing browser data. A share link contains the thread inputs and excludes private project notes.
Compare places up to four specifications side by side. Batch reads specifications from a CSV file; download its template for the column names and examples.
Job sheets open a printable view. Letter is the default paper size; select A4 when needed. Use the browser’s print dialog to print or save a PDF.