Thread Pitch Calculator

Calculate thread pitch, threads per inch (TPI), lead angle, and other critical thread dimensions in real-time. This tool supports both metric and imperial standards including UN, Metric, NPT, BSP, and ACME threads.

Thread Pitch Calculator

Metric (mm)
Imperial (inches)
Please enter a valid positive number
Please enter a valid positive number
Please enter a valid positive number
Simple thread profile diagram showing crests and roots Thread Profile Visualization
Thread Pitch
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Threads Per Inch (TPI)
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Lead
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Lead Angle
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How to Use the Thread Pitch Calculator

Our thread pitch calculator provides instant results as you type. Follow these steps for accurate measurements:

  1. Select your preferred unit system (Metric or Imperial)
  2. In the Basic tab, enter the threaded length and number of threads
  3. For advanced calculations, use the Advanced tab to input diameter, number of starts, and tolerance class
  4. Results update automatically in real-time

What is Thread Pitch?

Thread pitch is the distance between the same point on two adjacent threads. For metric threads, pitch is measured in millimeters between thread crests. For imperial threads, pitch is often expressed as threads per inch (TPI), which is the number of complete threads in one inch of threaded length.

How to Measure Thread Pitch

You can measure thread pitch using several methods:

  • Using a ruler: Measure the distance between adjacent thread crests
  • Thread pitch gauge: Match the gauge teeth to your threads for instant identification
  • Calculation method: Use the formula P = L / n, where P is pitch, L is length, and n is number of threads

Frequently Asked Questions

What is the difference between thread pitch and TPI? â–¼

Thread pitch and TPI (Threads Per Inch) are inversely related measurements of thread density. Pitch is the distance between threads (e.g., 1.5mm), while TPI counts how many threads fit in one inch (e.g., 20 TPI). For imperial threads, pitch = 1 / TPI.

How do I calculate thread pitch for a 2-inch long bolt with 48 threads? â–¼

Using the formula P = L / n, divide the length (2 inches) by the number of threads (48). This gives a thread pitch of 0.04167 inches. To convert to metric: multiply 2 inches by 25.4 mm/inch to get 50.8 mm, then divide by 48 threads to get 1.0583 mm pitch.

What does the second number in a metric thread callout mean? â–¼

In a metric thread callout like M10 × 1.5, the second number (1.5) represents the thread pitch in millimeters. For M36 × 4, the pitch is 4 millimeters.

How is lead different from pitch in threaded fasteners? â–¼

Pitch is the distance between adjacent threads, while lead is the distance the fastener advances in one complete revolution. For single-start threads, lead equals pitch. For multi-start threads, lead = pitch × number of starts.