Roller chain sprocket dimensions (ANSI): pitch diameter, outside diameter, caliper and tooth width, #25 to #80, 9 to 60 teeth — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/roller-chain-sprocket-dimensions-ansi/  (sheet CC BY 4.0)
Basis: ANSI sprocket formulas as printed by Martin Sprocket, Machinery's Handbook and Gizmology, tooth width checked against Martin's table; computed per tooth count; maker CAD linked
Catalog version: 2026-10-20

Sizes: see table below
- Formulas used for the table (all from the sources below; N = teeth, P = pitch, Dr = roller Ø): pitch Ø PD = P / sin(180° / N) (Martin, Gizmology); turned outside Ø OD = P × (0.6 + cot(180° / N)) (Martin, Machinery's Handbook, Gizmology); caliper Ø for an even tooth count = PD − Dr, for an odd count = PD × cos(90° / N) − Dr (Machinery's Handbook p. 1318; the page prints 'caliper factor = PD cos(90° ÷ N)'). Values are computed, not copied; PD of #40 with 20 teeth is 3.196 in (81.18 mm).
- OD is not critical to meshing (Martin): the table gives the turned OD above. Hob-cut and topped sprockets are a little different (OD = PD − Dr + 2 × the cutter's whole depth, Machinery's Handbook), and one forum tutorial uses OD = PD + P / 2; none of those figures are tabulated here, so check the maker's OD for a drawing. No source read gives a root-diameter formula, so none is tabulated; the caliper diameter is the practical check.
- Single-strand tooth width = 0.93 × inner width W − 0.006 in (Gizmology). It reproduces the first value of every row in Martin's single-strand tooth table for all six chains (#25 0.110, #35 0.168, #40 0.284, #50 0.343, #60 0.459, #80 0.575 in; #35 computes 0.169 against Martin's 0.168). Per-chain constants: #25: seat Ø Ds 0.1336 in (3.395 mm), seat radius R 0.0668 (1.697), working-curve radius E 0.1708 (4.339), ac 0.1040 (2.642), ab 0.1820 (4.623), single-strand tooth width 0.110 in (2.80 mm); #35: seat Ø Ds 0.2040 in (5.182 mm), seat radius R 0.1020 (2.591), working-curve radius E 0.2620 (6.655), ac 0.1600 (4.064), ab 0.2800 (7.112), single-strand tooth width 0.169 in (4.29 mm); #40: seat Ø Ds 0.3166 in (8.041 mm), seat radius R 0.1583 (4.020), working-curve radius E 0.4079 (10.360), ac 0.2496 (6.340), ab 0.4368 (11.095), single-strand tooth width 0.284 in (7.22 mm); #50: seat Ø Ds 0.4050 in (10.287 mm), seat radius R 0.2025 (5.143), working-curve radius E 0.5225 (13.271), ac 0.3200 (8.128), ab 0.5600 (14.224), single-strand tooth width 0.343 in (8.71 mm); #60: seat Ø Ds 0.4743 in (12.048 mm), seat radius R 0.2372 (6.024), working-curve radius E 0.6124 (15.554), ac 0.3752 (9.530), ab 0.6566 (16.678), single-strand tooth width 0.459 in (11.66 mm); #80: seat Ø Ds 0.6311 in (16.031 mm), seat radius R 0.3156 (8.015), working-curve radius E 0.8156 (20.715), ac 0.5000 (12.700), ab 0.8750 (22.225), single-strand tooth width 0.575 in (14.61 mm).
- ANSI B29.1 tooth-form constants read in the sources: seating-curve Ds = 1.005 Dr + 0.003 in (R = Ds / 2), working-curve radius E = 1.3025 Dr + 0.0015 in, G = 1.4 Dr (Machinery's Handbook p. 1330), seating angle A = 35° + 60° / N, B = 18° − 56° / N, ac = 0.8 Dr, ab = 1.4 Dr (Chief Delphi tutorial, which says the constants are from the ANSI standard). The remaining standard dimensions (chord yz, topping-curve radius F and offset H, S, W, V) could not be read from any source reachable here, so the full tooth outline is NOT drawn.
- No sprocket files: a tooth gap needs the whole ANSI outline, not just the seat arc, and the missing topping-curve numbers would have been invented. The existing roller-chain-sprockets page has #25 / #35 simplified-form files; its tooth form is labelled an approximation there. Martin says plate sprockets are normally made in sizes 7-1/2 in and larger, and type A (a plain plate with the tooth form and a bore) in all diameters; the plate thickness is the maker's choice.
- For a plate you intend to make yourself: use the PD, the seat Ø and the tooth width above, and cut the gaps with the maker's CAD (Tsubaki and Martin both offer it) or with the standard.

chain  teeth N  pitch Ø PD, in  pitch Ø PD, mm  turned OD, in  turned OD, mm  caliper Ø, in  caliper Ø, mm
#25  9  0.731  18.57  0.837  21.26  0.590  14.98
#25  10  0.809  20.55  0.919  23.35  0.679  17.25
#25  11  0.887  22.54  1.001  25.44  0.748  19.01
#25  12  0.966  24.53  1.083  27.51  0.836  21.23
#25  13  1.045  26.53  1.164  29.57  0.907  23.04
#25  14  1.123  28.54  1.245  31.63  0.993  25.23
#25  15  1.202  30.54  1.326  33.68  1.066  27.07
#25  16  1.281  32.55  1.407  35.73  1.151  29.25
#25  17  1.361  34.56  1.487  37.78  1.225  31.11
#25  18  1.440  36.57  1.568  39.82  1.310  33.27
#25  19  1.519  38.58  1.648  41.86  1.384  35.15
#25  20  1.598  40.59  1.728  43.90  1.468  37.29
#25  21  1.677  42.61  1.809  45.94  1.543  39.18
#25  22  1.757  44.62  1.889  47.98  1.627  41.32
#25  23  1.836  46.63  1.969  50.01  1.702  43.22
#25  24  1.915  48.65  2.049  52.04  1.785  45.35
#25  25  1.995  50.66  2.129  54.08  1.861  47.26
#25  28  2.233  56.71  2.369  60.17  2.103  53.41
#25  30  2.392  60.75  2.529  64.23  2.262  57.45
#25  32  2.551  64.78  2.688  68.28  2.421  61.48
#25  35  2.789  70.84  2.928  74.36  2.656  67.47
#25  36  2.868  72.86  3.008  76.39  2.738  69.56
#25  40  3.186  80.93  3.327  84.49  3.056  77.63
#25  45  3.584  91.03  3.725  94.62  3.452  87.67
#25  48  3.822  97.09  3.964  100.69  3.692  93.79
#25  50  3.981  101.13  4.124  104.74  3.851  97.83
#25  60  4.777  121.33  4.920  124.98  4.647  118.03
#35  9  1.096  27.85  1.255  31.88  0.880  22.35
#35  10  1.214  30.82  1.379  35.03  1.014  25.74
#35  11  1.331  33.81  1.502  38.15  1.118  28.38
#35  12  1.449  36.80  1.625  41.26  1.249  31.72
#35  13  1.567  39.80  1.746  44.36  1.356  34.43
#35  14  1.685  42.80  1.868  47.45  1.485  37.72
#35  15  1.804  45.81  1.989  50.53  1.594  40.48
#35  16  1.922  48.82  2.110  53.60  1.722  43.74
#35  17  2.041  51.84  2.231  56.67  1.832  46.54
#35  18  2.160  54.85  2.352  59.73  1.960  49.77
#35  19  2.278  57.87  2.472  62.80  2.071  52.59
#35  20  2.397  60.89  2.593  65.85  2.197  55.81
#35  21  2.516  63.91  2.713  68.91  2.309  58.65
#35  22  2.635  66.93  2.833  71.96  2.435  61.85
#35  23  2.754  69.95  2.953  75.01  2.548  64.71
#35  24  2.873  72.97  3.073  78.06  2.673  67.89
#35  25  2.992  76.00  3.193  81.11  2.786  70.77
#35  28  3.349  85.07  3.553  90.25  3.149  79.99
#35  30  3.588  91.12  3.793  96.34  3.388  86.04
#35  32  3.826  97.18  4.032  102.42  3.626  92.10
#35  35  4.183  106.26  4.392  111.55  3.979  101.07
#35  36  4.303  109.29  4.511  114.59  4.103  104.21
#35  40  4.780  121.40  4.990  126.74  4.580  116.32
#35  45  5.376  136.55  5.588  141.93  5.173  131.38
#35  48  5.734  145.64  5.946  151.04  5.534  140.56
#35  50  5.972  151.69  6.185  157.11  5.772  146.61
#35  60  7.165  182.00  7.380  187.46  6.965  176.92
#40  9  1.462  37.13  1.674  42.51  1.128  28.64
#40  10  1.618  41.10  1.839  46.71  1.306  33.17
#40  11  1.775  45.08  2.003  50.87  1.445  36.69
#40  12  1.932  49.07  2.166  55.02  1.620  41.14
#40  13  2.089  53.07  2.329  59.15  1.762  44.76
#40  14  2.247  57.07  2.491  63.26  1.935  49.15
#40  15  2.405  61.08  2.652  67.37  2.080  52.82
#40  16  2.563  65.10  2.814  71.47  2.251  57.17
#40  17  2.721  69.12  2.975  75.56  2.397  60.90
#40  18  2.879  73.14  3.136  79.65  2.567  65.21
#40  19  3.038  77.16  3.296  83.73  2.715  68.97
#40  20  3.196  81.18  3.457  87.80  2.884  73.26
#40  21  3.355  85.21  3.617  91.88  3.033  77.05
#40  22  3.513  89.24  3.778  95.95  3.201  81.31
#40  23  3.672  93.27  3.938  100.02  3.351  85.13
#40  24  3.831  97.30  4.098  104.09  3.519  89.37
#40  25  3.989  101.33  4.258  108.15  3.669  93.21
#40  28  4.466  113.43  4.738  120.34  4.154  105.50
#40  30  4.783  121.50  5.057  128.45  4.471  113.57
#40  32  5.101  129.57  5.377  136.57  4.789  121.64
#40  35  5.578  141.68  5.855  148.73  5.260  133.61
#40  36  5.737  145.72  6.015  152.78  5.425  137.79
#40  40  6.373  161.87  6.653  168.99  6.061  153.94
#40  45  7.168  182.06  7.450  189.24  6.851  174.03
#40  48  7.645  194.18  7.929  201.38  7.333  186.26
#40  50  7.963  202.26  8.247  209.48  7.651  194.34
#40  60  9.554  242.66  9.841  249.95  9.242  234.74
#50  9  1.827  46.42  2.092  53.14  1.400  35.55
#50  10  2.023  51.37  2.299  58.38  1.623  41.21
#50  11  2.218  56.35  2.504  63.59  1.796  45.61
#50  12  2.415  61.34  2.708  68.77  2.015  51.18
#50  13  2.612  66.33  2.911  73.93  2.193  55.69
#50  14  2.809  71.34  3.113  79.08  2.409  61.18
#50  15  3.006  76.35  3.315  84.21  2.590  65.78
#50  16  3.204  81.37  3.517  89.33  2.804  71.21
#50  17  3.401  86.39  3.718  94.45  2.987  75.87
#50  18  3.599  91.42  3.920  99.56  3.199  81.26
#50  19  3.797  96.45  4.120  104.66  3.384  85.96
#50  20  3.995  101.48  4.321  109.76  3.595  91.32
#50  21  4.193  106.51  4.522  114.85  3.782  96.06
#50  22  4.392  111.55  4.722  119.94  3.992  101.39
#50  23  4.590  116.59  4.922  125.02  4.179  106.15
#50  24  4.788  121.62  5.122  130.11  4.388  111.46
#50  25  4.987  126.66  5.322  135.19  4.577  116.25
#50  28  5.582  141.79  5.922  150.42  5.182  131.63
#50  30  5.979  151.87  6.321  160.57  5.579  141.71
#50  32  6.376  161.96  6.721  170.71  5.976  151.80
#50  35  6.972  177.10  7.319  185.91  6.565  166.76
#50  36  7.171  182.15  7.519  190.98  6.771  171.99
#50  40  7.966  202.33  8.316  211.24  7.566  192.17
#50  45  8.960  227.58  9.313  236.55  8.554  217.28
#50  48  9.556  242.73  9.911  251.73  9.156  232.57
#50  50  9.954  252.82  10.309  261.85  9.554  242.66
#50  60  11.942  303.33  12.301  312.44  11.542  293.17
#60  9  2.193  55.70  2.511  63.77  1.691  42.94
#60  10  2.427  61.65  2.758  70.06  1.958  49.73
#60  11  2.662  67.62  3.004  76.31  2.166  55.02
#60  12  2.898  73.60  3.249  82.53  2.429  61.69
#60  13  3.134  79.60  3.493  88.72  2.642  67.11
#60  14  3.370  85.61  3.736  94.89  2.901  73.70
#60  15  3.607  91.63  3.978  101.05  3.119  79.21
#60  16  3.844  97.65  4.221  107.20  3.375  85.73
#60  17  4.082  103.67  4.462  113.34  3.595  91.32
#60  18  4.319  109.70  4.703  119.47  3.850  97.79
#60  19  4.557  115.74  4.945  125.59  4.072  103.43
#60  20  4.794  121.78  5.185  131.71  4.325  109.86
#60  21  5.032  127.82  5.426  137.82  4.549  115.55
#60  22  5.270  133.86  5.666  143.93  4.801  121.95
#60  23  5.508  139.90  5.907  150.03  5.026  127.66
#60  24  5.746  145.95  6.147  156.13  5.277  134.04
#60  25  5.984  151.99  6.387  162.23  5.503  139.78
#60  28  6.699  170.14  7.106  180.50  6.230  158.23
#60  30  7.175  182.25  7.586  192.68  6.706  170.33
#60  32  7.652  194.35  8.065  204.85  7.183  182.44
#60  35  8.367  212.52  8.783  223.09  7.889  200.39
#60  36  8.605  218.57  9.023  229.17  8.136  206.66
#60  40  9.559  242.80  9.980  253.48  9.090  230.89
#60  45  10.752  273.09  11.175  283.86  10.276  261.01
#60  48  11.467  291.27  11.893  302.08  10.998  279.36
#60  50  11.944  303.39  12.371  314.22  11.475  291.48
#60  60  14.330  363.99  14.761  374.93  13.861  352.08
#80  9  2.924  74.26  3.347  85.03  2.254  57.26
#80  10  3.236  82.20  3.678  93.41  2.611  66.32
#80  11  3.549  90.16  4.006  101.74  2.888  73.36
#80  12  3.864  98.14  4.332  110.03  3.239  82.26
#80  13  4.179  106.14  4.657  118.29  3.523  89.49
#80  14  4.494  114.15  4.981  126.52  3.869  98.27
#80  15  4.810  122.17  5.305  134.74  4.158  105.62
#80  16  5.126  130.20  5.627  142.93  4.501  114.32
#80  17  5.442  138.23  5.950  151.12  4.794  121.77
#80  18  5.759  146.27  6.271  159.29  5.134  130.40
#80  19  6.076  154.32  6.593  167.45  5.430  137.92
#80  20  6.392  162.37  6.914  175.61  5.767  146.49
#80  21  6.710  170.42  7.235  183.76  6.066  154.07
#80  22  7.027  178.48  7.555  191.90  6.402  162.60
#80  23  7.344  186.54  7.876  200.04  6.702  170.23
#80  24  7.661  194.60  8.196  208.17  7.036  178.72
#80  25  7.979  202.66  8.516  216.30  7.338  186.38
#80  28  8.931  226.86  9.475  240.67  8.306  210.98
#80  30  9.567  243.00  10.114  256.90  8.942  227.12
#80  32  10.202  259.14  10.753  273.13  9.577  243.26
#80  35  11.156  283.36  11.711  297.46  10.520  267.20
#80  36  11.474  291.43  12.030  305.56  10.849  275.56
#80  40  12.745  323.74  13.306  337.98  12.120  307.86
#80  45  14.336  364.12  14.901  378.48  13.702  348.03
#80  48  15.290  388.36  15.857  402.77  14.665  372.49
#80  50  15.926  404.52  16.495  418.96  15.301  388.64
#80  60  19.107  485.33  19.681  499.90  18.482  469.45

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Martin Sprocket: Sprocket engineering data: PD = pitch / sin(180 / N), OD = pitch (0.6 + cot(180 / N)), roller width and diameter, single-strand tooth width table — web — Publisher's page; dimensions are facts — https://www.martinsprocket.com/docs/catalogs/engineering/engineering%20catalog/sprocket-engineering-data.pdf
- Machinery's Handbook, 31st ed.: Transmission roller chains: caliper diameter (PD cos(90 / N) − Dr for odd teeth), turned OD formula, working curve E = 1.3025 Dr + 0.0015 in, G = 1.4 Dr — web — Publisher's page; dimensions are facts — https://online.flippingbook.com/view/954046886/1318
- Machinery's Handbook, 31st ed.: Transmission roller chains, hob layout page: E and G for all ranges — web — Publisher's page; dimensions are facts — https://online.flippingbook.com/view/954046886/1330
- Chief Delphi (forum tutorial): Sprocket design tutorial: ANSI constants A = 35° + 60° / n, B = 18° − 56° / n, R = Ds / 2, Ds = 1.005 Dr + 0.003 in, ac = 0.8 Dr, ab = 1.4 Dr — web — Publisher's page; dimensions are facts — https://www.chiefdelphi.com/t/sprocket-design-tutorial/387449
- Gizmology (notes quoted on meslab.org): Notes on sprockets and chains: PD, OD and sprocket thickness = 0.93 × roller width − 0.006 in — web — Publisher's page; dimensions are facts — https://meslab.org/goto/post?id=71581
- ASME: ASME B29.1-2011 Precision power transmission roller chains, attachments, and sprockets (the standard itself, paid) — web — Publisher's page; dimensions are facts — https://webstore.ansi.org/standards/asme/asmeb292011r2022
- Tsubaki (US): Roller chain, sprockets and TAPER-LOCK bushings: maker catalogue with CAD downloads — web — Publisher's page; dimensions are facts — https://www.tsubaki.com/
- Martin Sprocket: Martin Sprocket & Gear CAD library (sprockets, QD and taper bushings) — web — Publisher's page; dimensions are facts — https://www.martinsprocket.com/

No true-size file yet: the published figures do not fix the whole shape; a measured scan is planned.
API: https://xemstudio.com/api/geometry?object=roller-chain-sprocket-dimensions-ansi