Gear Tooth Calculator
SI
Imp
Imperial
Inputs
View results
Size system
Specify gear size by metric module or imperial diametral pitch.
Module (metric)
Diametral pitch (imperial)
Module / DP
(m)
Module in mm or diametral pitch in 1/in.
mm
Pressure angle
(α)
Standard pressure angle. 20° is the common modern default.
14.5°
20°
25°
Tooth count
(z)
Number of teeth on the gear.
Profile shift
(x)
Addendum-modification coefficient. Positive shift increases tooth thickness and can avoid undercut.
Results
Default result
Edit inputs
Tooth thickness at pitch
(s)
3.142
mm
Also computed
Addendum
(a)
2
mm
Dedendum
(b)
2.5
mm
Whole depth
(hₜ)
4.5
mm
Circular pitch
(p)
6.283
mm
Base pitch
(p_b)
5.904
mm
Pitch diameter
(d)
40
mm
Base diameter
(d_b)
37.59
mm
Outside diameter
(d_a)
44
mm
Root diameter
(d_f)
35
mm
Undercut margin
Pass
2.9
Above the no-undercut minimum.
teeth above minimum
Show 4 more results
Method notes
3 notes
Standard full-depth involute reference: addendum = m, dedendum = 1.25m, whole depth = 2.25m when profile shift x = 0.
Tooth thickness at the pitch circle is s = m·(π/2 + 2x·tan α).
Minimum teeth to avoid undercut at 20° is 18 without profile shift.
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