Thread Pitch and Lead
Thread pitch, lead, and sharp-V height for inch and metric threads.
Example
You enter
- Thread standard inch
- Threads per inch (TPI) 20
- Number of starts 1
You get
- Pitch 0.05
- Pitch (mm) 1.27
- Threads per inch 20 TPI
- Lead (per turn) 0.05
- 60-deg sharp-V height 0.0433013
Details, formula, and sources
Thread pitch, lead, and 60-degree sharp-V height for UN/UNC/UNF inch (pitch = 1 / TPI) and ISO metric (pitch in mm) threads: lead = pitch x starts, H = pitch x sqrt(3)/2 (first-principles 60-degree thread geometry).
Inch: P = 1 / TPI. Metric: P is the pitch in mm, TPI = 25.4 / P. Lead = P * starts. Sharp-V 60-degree height H = P * cos(30) = P * sqrt(3) / 2.
Thread pitch, lead, and 60-degree form - Unified (UN/UNC/UNF) inch and ISO metric threads share a 60-degree included angle - as in Machinery's Handbook (Industrial Press), by name; first-principles geometry.
Pure geometry, public; the truncated thread depth and the tap-drill size are thread-form- and class-specific and are not computed here.
Estimate. AHJ and licensed professional govern.
Field names used by the API: thread_standard, tpi, starts, pitch_in, pitch_mm, lead_in, sharp_v_height_in
- Thread form 60-degree included angle (UN/UNC/UNF and ISO metric); Acme, buttress, and pipe-thread forms are not coveredthread-form geometry