Solve helix lead angle from pitch, starts, and diameter. Review formulas, steps, examples, and exports. Clear results appear instantly above the responsive input form.
Use the same unit for all length inputs.
| Pitch | Starts | Lead | Mean Diameter | Lead Angle (°) |
|---|---|---|---|---|
| 2 | 1 | 2 | 16 | 2.2785 |
| 2.5 | 2 | 5 | 20 | 4.5499 |
| 3 | 2 | 6 | 25 | 4.3686 |
| 4 | 3 | 12 | 32 | 6.807 |
| 5 | 4 | 20 | 40 | 9.0431 |
These sample rows use one consistent length unit throughout the calculation.
The calculator uses the helix relation for lead angle. The main formula is tan(λ) = L / C, where λ is lead angle, L is lead, and C is the circumference of one turn.
When mean diameter is known, circumference becomes C = π × d. That gives λ = arctan(L / (π × d)). When mean radius is known, circumference becomes C = 2π × r.
For multi-start threads, lead is not the same as pitch. In that case, lead is computed with L = pitch × starts. The tool also supports reverse planning with L = C × tan(λ).
Lead angle is the angle of a helix measured from a plane perpendicular to the axis. In screws and threads, it shows how steeply the path rises in one revolution.
Mean diameter represents the effective circular path used by the helix. Using only outside diameter can shift the result when thread depth or groove depth matters.
Not always. For a single-start thread, lead equals pitch. For multi-start threads, lead equals pitch multiplied by the number of starts.
Yes. Keep lead, pitch, radius, diameter, and circumference in the same unit system. Consistent geometry keeps the angle result correct.
Yes. Use the target-angle mode. It rearranges the formula and calculates the lead needed for the selected mean diameter.
Slope percent is the lead divided by circumference, multiplied by 100. It provides a quick comparison of helix steepness without converting angles mentally.
Helix length per turn estimates the actual distance along one spiral revolution. It helps when comparing motion path length, surface travel, or winding distance.
Yes. The CSV and PDF exports use the currently displayed result and precision. Increase decimal places first when you need finer output detail.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.