Gear Diametral Pitch, Module Conversion Table Chart

Gear Application and Design Resources

The following charts convert gear pitch dimensional data to the following:

Diametral Pitch, Module, Circular Pitch

Module: is the unit of size that indicates how big or small a gear is. It is the ratio of the reference diameter of the gear divided by the number of teeth.

Module = (Reference Diameter) / (Number of Teeth)
m = d / z

Diametric, module and circular pitches Conversion.

Diametral Pitch Circular
Pitch in Inches
Circular Pitch
in Millimeters
Module In
Millimeters
20
24
25.3995
31.4159
31.7653
32
36.2857
42.3333
48
50.8348
63.5950
64
72
80
84.6198
96
101.6697
120
127.1899
200
.1571
.1309
.1237
.100
.0989
.0982
.0856
.0742
.0654
.0618
.0494
.0491
.0436
.0393
.0371
.0327
.0309
.0262
.0247
.0157
3.990
3.325
3.142
2.540
2.513
2.494
2.199
1.885
1.661
1.571
1.256
1.247
1.107
.998
.943
.831
.785
.665
.628
.399
1.2700
1.0583
1.0
.8085
.8
.7938
.7
.6
.5288
.5
.4
.3969
.3524
.3177
.3
.2645
.25
.2116
.2
.127

 Spur Gear Conversion
(Units in inches)

Standard
Stock
Pitches
Addendum Dedendum Whole
Depth
Circular
Pitch
20
24
1/10
32
48
64
72
80
96
120
200
.0500
.0417
.0318
.0313
.0208
.0156
.0139
.0125
.0104
.0083
.0050
.0579
.0520
.0402
.0395
.0270
.0208
.0187
.0170
.0145
.0120
.0080
.1079
.0937
.0720
.0708
.0478
.0364
.0326
.0295
.0249
.0203
.0130
.1571
.1309
.1000
.0982
.0654
.0491
.0436
.0393
.0327
.0262
.0157

Common Gear Pitches by Decimal Size (Units in inches)

Diametral Pitch (inch)
Circular Pitch (inch)
Module
0.3387
9.2764
75
0.3629
8.658
70
0.3908
8.0395
65
0.4233
7.4211
60
0.4618
6.8027
55
0.5
6.2832
50.8
0.508
6.1843
50
0.5644
5.5658
45
0.6048
5.1948
42
0.6513
4.8237
39
0.7056
4.4527
36
0.75
4.1888
33.867
0.7697
4.0816
33
0.7854
4
12.128
0.8467
3.7106
30
0.8976
3.5
12
0.9407
3.3395
27
1
3.1416
25.4
1.0472
3
11.622
1.0583
2.9684
24
1.1424
2.75
11.289
1.1545
2.7211
22
1.25
2.5133
20.32
1.2566
2.5
11.117
1.27
2.4737
20
1.3963
2.25
11
1.4111
2.2263
18
1.5
2.0944
16.933
1.5708
2
10.612
1.5875
1.979
16
1.6755
1.875
10.16
1.6933
1.8553
15
1.75
1.7952
14.514
1.7952
1.75
10
1.8143
1.7316
14
1.9333
1.625
9.236
1.9538
1.6079
13
2
1.5708
12.7
2.0944
1.5
9.096
2.1167
1.4842
12
2.1855
1.4375
9
2.25
1.3963
11.289
2.2848
1.375
8.59
2.3091
1.3605
11
2.3936
1.3125
8.467
2.5
1.2566
10.16
2.54
1.2369
10
2.75
1.1424
9.236
2.7925
1.125
8.085
2.8222
1.1132
9
2.9568
1.0625
8
3
1.0472
8.467
3.1416
1
7.58
3.175
0.9895
8
3.351
0.9375
7.257
3.5
0.8976
7.257
3.5904
0.875
7.074
3.6286
0.8658
7
3.8666
0.8125
7
3.9077
0.804
6.5
4
0.7854
6.35
4.1888
0.75
6.569
4.2333
0.7421
6
4.5
0.6981
5.644
4.5696
0.6875
6.5
4.6182
0.6803
5.5
4.71
0.667
6.35
5
0.6283
5.08
5.0266
0.625
6.064
5.08
0.6184
5
5.5851
0.5625
6
5.6444
0.5566
4.5
6
0.5236
4.233
6.2832
0.5
5.644
6.35
0.4947
4
6.7733
0.4638
3.75
7
0.4488
3.629
7.1808
0.4375
5.558
7.2571
0.4329
3.5
7.8154
0.402
3.25
7.854
0.4
5.5
8
0.3927
3.175
8.3776
0.375
5.393
8.4667
0.3711
3
9
0.3491
2.822
9.2364
0.3401
2.75
9.4342
0.333
5.08
10
0.3142
2.54
10.0531
0.3125
5.053
10.16
0.3092
2.5
10.9846
0.286
5
11
0.2856
2.309
11.2889
0.2783
2.25
12
0.2618
2.117
12.5664
0.25
4.548
12.7
0.2474
2
13
0.2417
1.954
14
0.2244
1.814
14.1514
0.222
4.5
14.5143
0.2164
1.75
15
0.2094
1.693
15.708
0.2
4.233
16
0.1964
1.588
16.7552
0.1875
4.043
16.9333
0.1855
1.5
17
0.1848
1.494
18
0.1745
1.411
18.812
0.167
4
19
0.1653
1.337
20
0.1571
1.27
20.32
0.1546
1.25
22
0.1428
1.155
24
0.1309
1.058
25.4
0.1237
1
26
0.1208
0.977
28
0.1122
0.907
28.2222
0.1113
0.9
30
0.1047
0.847
31.75
0.0989
0.8
32
0.0982
0.794
34
0.0924
0.747
36
0.0873
0.706
36.2857
0.0866
0.7
42.3333
0.0742
0.6
50.8
0.0618
0.5
63.5
0.0495
0.4
84.6667
0.0371
0.3

Gear Pitch Conversion Table Chart
(Units in inches)

Diametral Pitch
Circular Pitch
Module
Diametral Pitch
Circular Pitch
Module
Diametral Pitch
0.3387
9.2764
75
2.3091
1.3605
11
9.4342
0.3629
8.658
70
2.3936
1.3125
8.467
10
0.3908
8.0395
65
2.5
1.2566
10.16
10.0531
0.4233
7.4211
60
2.54
1.2369
10
10.16
0.4618
6.8027
55
2.75
1.1424
9.236
10.9846
0.5
6.2832
50.8
2.7925
1.125
8.085
11
0.508
6.1843
50
2.8222
1.1132
9
11.2889
0.5644
5.5658
45
2.9568
1.0625
8
12
0.6048
5.1948
42
3
1.0472
8.467
12.5664
0.6513
4.8237
39
3.1416
1
7.58
12.7
0.7056
4.4527
36
3.175
0.9895
8
13
0.75
4.1888
33.867
3.351
0.9375
7.257
14
0.7697
4.0816
33
3.5
0.8976
7.257
14.1514
0.7854
4
12.128
3.5904
0.875
7.074
14.5143
0.8467
3.7106
30
3.6286
0.8658
7
15
0.8976
3.5
12
3.8666
0.8125
7
15.708
0.9407
3.3395
27
3.9077
0.804
6.5
16
1
3.1416
25.4
4
0.7854
6.35
16.7552
1.0472
3
11.622
4.1888
0.75
6.569
16.9333
1.0583
2.9684
24
4.2333
0.7421
6
17
1.1424
2.75
11.289
4.5
0.6981
5.644
18
1.1545
2.7211
22
4.5696
0.6875
6.5
18.812
1.25
2.5133
20.32
4.6182
0.6803
5.5
19
1.2566
2.5
11.117
4.71
0.667
6.35
20
1.27
2.4737
20
5
0.6283
5.08
20.32
1.3963
2.25
11
5.0266
0.625
6.064
22
1.4111
2.2263
18
5.08
0.6184
5
24
1.5
2.0944
16.933
5.5851
0.5625
6
25.4
1.5708
2
10.612
5.6444
0.5566
4.5
26
1.5875
1.979
16
6
0.5236
4.233
28
1.6755
1.875
10.16
6.2832
0.5
5.644
28.2222
1.6933
1.8553
15
6.35
0.4947
4
30
1.75
1.7952
14.514
6.7733
0.4638
3.75
31.75
1.7952
1.75
10
7
0.4488
3.629
32
1.8143
1.7316
14
7.1808
0.4375
5.558
34
1.9333
1.625
9.236
7.2571
0.4329
3.5
36
1.9538
1.6079
13
7.8154
0.402
3.25
36.2857
2
1.5708
12.7
7.854
0.4
5.5
42.3333
2.0944
1.5
9.096
8
0.3927
3.175
50.8
2.1167
1.4842
12
8.3776
0.375
5.393
63.5
2.1855
1.4375
9
8.4667
0.3711
3
84.6667
2.25
1.3963
11.289
9
0.3491
2.822
-
2.2848
1.375
8.59
9.2364
0.3401
2.75
-

 

Diametral Pitch
Circular Pitch
Module
9.4342
0.333
5.08
10
0.3142
2.54
10.0531
0.3125
5.053
10.16
0.3092
2.5
10.9846
0.286
5
11
0.2856
2.309
11.2889
0.2783
2.25
12
0.2618
2.117
12.5664
0.25
4.548
12.7
0.2474
2
13
0.2417
1.954
14
0.2244
1.814
14.1514
0.222
4.5
14.5143
0.2164
1.75
15
0.2094
1.693
15.708
0.2
4.233
16
0.1964
1.588
16.7552
0.1875
4.043
16.9333
0.1855
1.5
17
0.1848
1.494
18
0.1745
1.411
18.812
0.167
4
19
0.1653
1.337
20
0.1571
1.27
20.32
0.1546
1.25
22
0.1428
1.155
24
0.1309
1.058
25.4
0.1237
1
26
0.1208
0.977
28
0.1122
0.907
28.2222
0.1113
0.9
30
0.1047
0.847
31.75
0.0989
0.8
32
0.0982
0.794
34
0.0924
0.747
36
0.0873
0.706
36.2857
0.0866
0.7
42.3333
0.0742
0.6
50.8
0.0618
0.5
63.5
0.0495
0.4
84.6667
0.0371
0.3
-
-
-
-
-
-