Involute splines ANSI B92.1 (30° flat root, side fit): pitch, major and minor diameters by tooth count, 5/10 to 48/96 + example shaft STEP/STL — dimension sheet Source: Xem Studio, https://xemstudio.com/objects/involute-splines-ansi-b92-1-30deg-flat-root/ (sheet CC BY 4.0) Basis: ANSI B92.1 30° flat-root side-fit formulas as published by Engineers Edge, pitch series and tooth range from Machinery's Handbook Table 3; basic dimensions, no tolerance; true involute shaft sections drawn from them Catalog version: 2026-10-20 Sizes: see table below - ANSI B92.1 involute splines are named by two diametral pitches, P / Ps (for example 16/32): P sets the pitch diameter D = N / P and the tooth thickness, Ps = 2 P (the 'stub' pitch) sets the shallow tooth height. This page is the 30° pressure angle, flat-root, side-fit form. Formulas (Engineers Edge's copy of the ANSI B92.1-1970, R1993 table): D = N / P; base Ø = D cos 30°; circular pitch π / P; minimum effective space width π / (2 P); major Ø external Do = (N + 1) / P; minor Ø internal Di = (N − 1) / P; minor Ø external Dre = (N − 1.35) / P for 2.5/5 to 12/24 pitch and (N − 1.2) / P for 16/32 and finer; major Ø internal Dri = (N + 1.35) / P; form diameters DFi = (N + 1) / P + 2 cF and DFe = (N − 1) / P − 2 cF with form clearance cF = 0.001 D (max 0.010, min 0.002 in). - Machinery's Handbook Table 3 (ANSI B92.1-1996) lists the pitch series 2.5/5, 3/6, 4/8, 5/10, 6/12, 8/16, 10/20, 12/24, 16/32, 20/40, 24/48, 32/64, 40/80, 48/96, 64/128, 80/160, 128/256, tooth numbers 6 to 60 at 30° and 37.5° (6 to 100 at 45°), and says odd tooth counts have no advantage. The table here covers pitches 5/10 to 48/96 and eight common tooth counts; any other N follows from the formulas. Dri for 16/32 and finer is left blank: the one formula table read prints a single Dri = (N + 1.35) / P line while it splits Dre by pitch, and the second line for fine pitches could not be confirmed, so it is not guessed. Fillet-root (30°, 37.5°, 45°) and major-diameter-fit forms are not tabulated. - Tolerances: ANSI B92.1 gives classes 4, 5, 6 and 7 (class 5 is the base; class 4 is 0.71 times, 6 is 1.40 times, 7 is 2.00 times its tolerance), actual tooth thickness and space width are offset from the basic values for fit, and an internal spline is cut to the effective space width. All values in the table are basic (nominal) dimensions before those allowances; apply your process's clearance on mating parts only. - Files: 14 example external spline shaft sections (pitch and tooth count in the file name), 1 in long, as one extruded solid with the basic tooth: pitch diameter D, major diameter Do and minor diameter Dre from the table, true involute flanks at 30° with tooth thickness half the circular pitch. The 1 in length is an example. Where the standard has a root fillet below the form diameter, the file carries the involute flank straight down to the root circle (a simplification; the contact region is exact). No internal splines are drawn because the internal root and form details beyond the table were not read. - Maker CAD: spline shafts and hubs are sold by Misumi-type and inch-pitch suppliers per part; the standard itself (ANSI B92.1-1996) is sold by ANSI / SAE and is linked, not reproduced. pitch P / Ps teeth N pitch Ø D = N / P, in (mm) major Ø external Do = (N + 1) / P minor Ø external Dre minor Ø internal Di = (N − 1) / P major Ø internal Dri 5/10 10 2 (50.80) 2.2 (55.88) 1.73 (43.94) 1.8 (45.72) 2.27 (57.66) 5/10 12 2.4 (60.96) 2.6 (66.04) 2.13 (54.10) 2.2 (55.88) 2.67 (67.82) 5/10 16 3.2 (81.28) 3.4 (86.36) 2.93 (74.42) 3 (76.20) 3.47 (88.14) 5/10 20 4 (101.60) 4.2 (106.68) 3.73 (94.74) 3.8 (96.52) 4.27 (108.46) 5/10 24 4.8 (121.92) 5 (127.00) 4.53 (115.06) 4.6 (116.84) 5.07 (128.78) 5/10 30 6 (152.40) 6.2 (157.48) 5.73 (145.54) 5.8 (147.32) 6.27 (159.26) 5/10 36 7.2 (182.88) 7.4 (187.96) 6.93 (176.02) 7 (177.80) 7.47 (189.74) 5/10 48 9.6 (243.84) 9.8 (248.92) 9.33 (236.98) 9.4 (238.76) 9.87 (250.70) 6/12 10 1.6667 (42.33) 1.8333 (46.57) 1.4417 (36.62) 1.5 (38.10) 1.8917 (48.05) 6/12 12 2 (50.80) 2.1667 (55.03) 1.775 (45.09) 1.8333 (46.57) 2.225 (56.52) 6/12 16 2.6667 (67.73) 2.8333 (71.97) 2.4417 (62.02) 2.5 (63.50) 2.8917 (73.45) 6/12 20 3.3333 (84.67) 3.5 (88.90) 3.1083 (78.95) 3.1667 (80.43) 3.5583 (90.38) 6/12 24 4 (101.60) 4.1667 (105.83) 3.775 (95.88) 3.8333 (97.37) 4.225 (107.32) 6/12 30 5 (127.00) 5.1667 (131.23) 4.775 (121.28) 4.8333 (122.77) 5.225 (132.72) 6/12 36 6 (152.40) 6.1667 (156.63) 5.775 (146.68) 5.8333 (148.17) 6.225 (158.12) 6/12 48 8 (203.20) 8.1667 (207.43) 7.775 (197.48) 7.8333 (198.97) 8.225 (208.91) 8/16 10 1.25 (31.75) 1.375 (34.92) 1.0813 (27.46) 1.125 (28.57) 1.4187 (36.04) 8/16 12 1.5 (38.10) 1.625 (41.27) 1.3313 (33.81) 1.375 (34.92) 1.6687 (42.39) 8/16 16 2 (50.80) 2.125 (53.97) 1.8313 (46.51) 1.875 (47.62) 2.1688 (55.09) 8/16 20 2.5 (63.50) 2.625 (66.67) 2.3312 (59.21) 2.375 (60.32) 2.6688 (67.79) 8/16 24 3 (76.20) 3.125 (79.38) 2.8312 (71.91) 2.875 (73.02) 3.1688 (80.49) 8/16 30 3.75 (95.25) 3.875 (98.42) 3.5812 (90.96) 3.625 (92.07) 3.9188 (99.54) 8/16 36 4.5 (114.30) 4.625 (117.47) 4.3312 (110.01) 4.375 (111.12) 4.6688 (118.59) 8/16 48 6 (152.40) 6.125 (155.57) 5.8312 (148.11) 5.875 (149.22) 6.1688 (156.69) 10/20 10 1 (25.40) 1.1 (27.94) 0.865 (21.97) 0.9 (22.86) 1.135 (28.83) 10/20 12 1.2 (30.48) 1.3 (33.02) 1.065 (27.05) 1.1 (27.94) 1.335 (33.91) 10/20 16 1.6 (40.64) 1.7 (43.18) 1.465 (37.21) 1.5 (38.10) 1.735 (44.07) 10/20 20 2 (50.80) 2.1 (53.34) 1.865 (47.37) 1.9 (48.26) 2.135 (54.23) 10/20 24 2.4 (60.96) 2.5 (63.50) 2.265 (57.53) 2.3 (58.42) 2.535 (64.39) 10/20 30 3 (76.20) 3.1 (78.74) 2.865 (72.77) 2.9 (73.66) 3.135 (79.63) 10/20 36 3.6 (91.44) 3.7 (93.98) 3.465 (88.01) 3.5 (88.90) 3.735 (94.87) 10/20 48 4.8 (121.92) 4.9 (124.46) 4.665 (118.49) 4.7 (119.38) 4.935 (125.35) 12/24 10 0.8333 (21.17) 0.9167 (23.28) 0.7208 (18.31) 0.75 (19.05) 0.9458 (24.02) 12/24 12 1 (25.40) 1.0833 (27.52) 0.8875 (22.54) 0.9167 (23.28) 1.1125 (28.26) 12/24 16 1.3333 (33.87) 1.4167 (35.98) 1.2208 (31.01) 1.25 (31.75) 1.4458 (36.72) 12/24 20 1.6667 (42.33) 1.75 (44.45) 1.5542 (39.48) 1.5833 (40.22) 1.7792 (45.19) 12/24 24 2 (50.80) 2.0833 (52.92) 1.8875 (47.94) 1.9167 (48.68) 2.1125 (53.66) 12/24 30 2.5 (63.50) 2.5833 (65.62) 2.3875 (60.64) 2.4167 (61.38) 2.6125 (66.36) 12/24 36 3 (76.20) 3.0833 (78.32) 2.8875 (73.34) 2.9167 (74.08) 3.1125 (79.06) 12/24 48 4 (101.60) 4.0833 (103.72) 3.8875 (98.74) 3.9167 (99.48) 4.1125 (104.46) 16/32 10 0.625 (15.88) 0.6875 (17.46) 0.55 (13.97) 0.5625 (14.29) not read (see note) 16/32 12 0.75 (19.05) 0.8125 (20.64) 0.675 (17.14) 0.6875 (17.46) not read (see note) 16/32 16 1 (25.40) 1.0625 (26.99) 0.925 (23.50) 0.9375 (23.81) not read (see note) 16/32 20 1.25 (31.75) 1.3125 (33.34) 1.175 (29.84) 1.1875 (30.16) not read (see note) 16/32 24 1.5 (38.10) 1.5625 (39.69) 1.425 (36.20) 1.4375 (36.51) not read (see note) 16/32 30 1.875 (47.62) 1.9375 (49.21) 1.8 (45.72) 1.8125 (46.04) not read (see note) 16/32 36 2.25 (57.15) 2.3125 (58.74) 2.175 (55.24) 2.1875 (55.56) not read (see note) 16/32 48 3 (76.20) 3.0625 (77.79) 2.925 (74.29) 2.9375 (74.61) not read (see note) 20/40 10 0.5 (12.70) 0.55 (13.97) 0.44 (11.18) 0.45 (11.43) not read (see note) 20/40 12 0.6 (15.24) 0.65 (16.51) 0.54 (13.72) 0.55 (13.97) not read (see note) 20/40 16 0.8 (20.32) 0.85 (21.59) 0.74 (18.80) 0.75 (19.05) not read (see note) 20/40 20 1 (25.40) 1.05 (26.67) 0.94 (23.88) 0.95 (24.13) not read (see note) 20/40 24 1.2 (30.48) 1.25 (31.75) 1.14 (28.96) 1.15 (29.21) not read (see note) 20/40 30 1.5 (38.10) 1.55 (39.37) 1.44 (36.58) 1.45 (36.83) not read (see note) 20/40 36 1.8 (45.72) 1.85 (46.99) 1.74 (44.20) 1.75 (44.45) not read (see note) 20/40 48 2.4 (60.96) 2.45 (62.23) 2.34 (59.44) 2.35 (59.69) not read (see note) 24/48 10 0.4167 (10.58) 0.4583 (11.64) 0.3667 (9.31) 0.375 (9.52) not read (see note) 24/48 12 0.5 (12.70) 0.5417 (13.76) 0.45 (11.43) 0.4583 (11.64) not read (see note) 24/48 16 0.6667 (16.93) 0.7083 (17.99) 0.6167 (15.66) 0.625 (15.88) not read (see note) 24/48 20 0.8333 (21.17) 0.875 (22.22) 0.7833 (19.90) 0.7917 (20.11) not read (see note) 24/48 24 1 (25.40) 1.0417 (26.46) 0.95 (24.13) 0.9583 (24.34) not read (see note) 24/48 30 1.25 (31.75) 1.2917 (32.81) 1.2 (30.48) 1.2083 (30.69) not read (see note) 24/48 36 1.5 (38.10) 1.5417 (39.16) 1.45 (36.83) 1.4583 (37.04) not read (see note) 24/48 48 2 (50.80) 2.0417 (51.86) 1.95 (49.53) 1.9583 (49.74) not read (see note) 32/64 10 0.3125 (7.94) 0.3438 (8.73) 0.275 (6.99) 0.2812 (7.14) not read (see note) 32/64 12 0.375 (9.52) 0.4062 (10.32) 0.3375 (8.57) 0.3438 (8.73) not read (see note) 32/64 16 0.5 (12.70) 0.5312 (13.49) 0.4625 (11.75) 0.4688 (11.91) not read (see note) 32/64 20 0.625 (15.88) 0.6562 (16.67) 0.5875 (14.92) 0.5938 (15.08) not read (see note) 32/64 24 0.75 (19.05) 0.7812 (19.84) 0.7125 (18.10) 0.7188 (18.26) not read (see note) 32/64 30 0.9375 (23.81) 0.9688 (24.61) 0.9 (22.86) 0.9062 (23.02) not read (see note) 32/64 36 1.125 (28.57) 1.1562 (29.37) 1.0875 (27.62) 1.0938 (27.78) not read (see note) 32/64 48 1.5 (38.10) 1.5312 (38.89) 1.4625 (37.15) 1.4688 (37.31) not read (see note) 40/80 10 0.25 (6.35) 0.275 (6.99) 0.22 (5.59) 0.225 (5.71) not read (see note) 40/80 12 0.3 (7.62) 0.325 (8.25) 0.27 (6.86) 0.275 (6.99) not read (see note) 40/80 16 0.4 (10.16) 0.425 (10.79) 0.37 (9.40) 0.375 (9.52) not read (see note) 40/80 20 0.5 (12.70) 0.525 (13.33) 0.47 (11.94) 0.475 (12.06) not read (see note) 40/80 24 0.6 (15.24) 0.625 (15.88) 0.57 (14.48) 0.575 (14.60) not read (see note) 40/80 30 0.75 (19.05) 0.775 (19.68) 0.72 (18.29) 0.725 (18.41) not read (see note) 40/80 36 0.9 (22.86) 0.925 (23.50) 0.87 (22.10) 0.875 (22.22) not read (see note) 40/80 48 1.2 (30.48) 1.225 (31.12) 1.17 (29.72) 1.175 (29.84) not read (see note) 48/96 10 0.2083 (5.29) 0.2292 (5.82) 0.1833 (4.66) 0.1875 (4.76) not read (see note) 48/96 12 0.25 (6.35) 0.2708 (6.88) 0.225 (5.71) 0.2292 (5.82) not read (see note) 48/96 16 0.3333 (8.47) 0.3542 (9.00) 0.3083 (7.83) 0.3125 (7.94) not read (see note) 48/96 20 0.4167 (10.58) 0.4375 (11.11) 0.3917 (9.95) 0.3958 (10.05) not read (see note) 48/96 24 0.5 (12.70) 0.5208 (13.23) 0.475 (12.06) 0.4792 (12.17) not read (see note) 48/96 30 0.625 (15.88) 0.6458 (16.40) 0.6 (15.24) 0.6042 (15.35) not read (see note) 48/96 36 0.75 (19.05) 0.7708 (19.58) 0.725 (18.41) 0.7292 (18.52) not read (see note) 48/96 48 1 (25.40) 1.0208 (25.93) 0.975 (24.76) 0.9792 (24.87) not read (see note) Files elsewhere (not hosted by Xem Studio; license as stated by the publisher): - Engineers Edge: Involute Spline (ANSI B92.1-1970, R1993), 30 deg flat root side fit: D = N/P, Do = (N+1)/P, Dre = (N-1.35)/P or (N-1.2)/P, Di = (N-1)/P, Dri = (N+1.35)/P — web — Publisher's page; dimensions are facts — https://www.engineersedge.com/gears/involute_spline_13649.htm - Machinery's Handbook, 31st ed. (online edition): Table 3: basic dimensions for involute splines ANSI B92.1-1996: pitch series 2.5/5 to 128/256, 6 to 60 teeth at 30 degrees — web — Publisher's page; dimensions are facts — https://online.flippingbook.com/view/954046886/1000 - ANSI / SAE: ANSI B92.1-1996 Involute splines and inspection (standard; sold, not reproduced) — standard — ANSI / SAE; dimensions are facts [verify license at link] — https://webstore.ansi.org/standards/sae/ansib921996 Free files (CC BY 4.0, Xem Studio; STEP + STL, 14 parts): https://xemstudio.com/files/hardware/involute-splines-ansi-b92-1-30deg-flat-root/index.json API: https://xemstudio.com/api/geometry?object=involute-splines-ansi-b92-1-30deg-flat-root