# Spur gears, 12 diametral pitch (DP): 12 to 60 teeth, 14.5° and 20° involute, pitch / outside / root diameter and STEP/STL

> What is the pitch diameter, outside diameter and root diameter of a 12 DP spur gear, and how many teeth does it have?

- Category: Hardware › Bearings, rails & motion
- Kind: Hardware
- Basis: AGMA / ANSI diametral-pitch relations: pitch Ø = N / DP, outside Ø = (N + 2) / DP, minimum dedendum per ANSI B6.1 (20° coarse), Machinery's Handbook (14.5°) and ANSI B6.7 (20 DP and finer); true involute flanks generated point by point
- Page: https://xemstudio.com/objects/spur-gears-dp-12/ · JSON: https://xemstudio.com/api/geometry?object=spur-gears-dp-12 · Plain text: https://xemstudio.com/objects/spur-gears-dp-12/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** Every file is drawn at true size with no tolerance added. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your process's clearance before making the part.

## Notes

- 12 diametral pitch (DP) means 12 teeth per inch of pitch diameter: pitch diameter = N / 12 in, outside diameter = (N + 2) / 12 in, circular pitch = π / 12 = 0.2618 in (6.650 mm), addendum 1 / 12 = 0.0833 in (2.117 mm), tooth thickness on the pitch circle π / (2 × 12) = 0.1309 in. Centre distance of two gears = (N1 + N2) / (2 × 12) in = 1.058 (N1 + N2) mm. Module equivalent: 2.1167. A 12 DP gear does not mesh with a metric module gear unless the two are within rounding of each other; use the module pages for metric gears.
- Below 20 DP the coarse-pitch proportions apply: 20° (ANSI B6.1) dedendum 1.25 / P, whole depth 2.25 / P; 14.5° dedendum 1.157 / P, whole depth 2.157 / P (all minimum values), so the 14.5° root circle is a little larger. The table lists root and base diameters for both pressure angles so a hob or a CAD mate can be checked. 14.5° and 20° gears do not mesh: the pair must have the same DP and the same pressure angle. 14.5° is the older Brown & Sharpe / Boston Gear stock form (undercut below 32 teeth), 20° the current standard (undercut below 18 teeth).
- Files: 26 gears, a 14.5° and a 20° gear for each of the 13 tooth counts, as one extruded solid with a plain bore. Flanks are the true involute of the base circle, tooth thickness on the pitch circle half the circular pitch (no backlash), outside and root diameters as in the table, the root circle held at the root diameter for every tooth count (the flank is carried down to it; the real root fillet and trochoid are not modelled). Example choices (not published values): face width 11/16 in (17.46 mm), which is 8 / DP rounded to 1/16 in, and a bore of about a third of the root diameter picked from 1/16, 1/8, 3/16, 1/4, 5/16, 3/8, 1/2, 5/8, 3/4, 1 in. Hubs, keyways and set-screw holes are not drawn. Teeth below 32 (14.5°) and 18 (20°) are drawn without profile shift, so they are undercut-prone as real unshifted gears are.
- Stock tooth counts: the 12 to 60 range covers common stock gears (Boston Gear lists 16 DP 14.5° 14-tooth with 0.875 in pitch diameter, 1 in outside diameter, 0.5 in face, 0.375 in bore, which the formulas above reproduce; SDP/SI lists 48 DP gears from 14 to 108 teeth). Face widths and bores of stock gears vary by maker and series; those are not a standard.
- Left out: the 25° pressure angle, stub and profile-shifted teeth, tolerances (AGMA quality numbers), backlash allowances, helical and bevel forms, and hub dimensions. Maker CAD: SDP/SI publishes inch-pitch spur gears with per-part CAD; linked, not copied.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| bore | plain bore, example Ø per file (1/16 to 1 in, see the table) | shaft of the same Ø | slide | gear-* |
| centre distance | (N1 + N2) / (2 × 12) in = 1.0583 (N1 + N2) mm | a second 12 DP gear of the same pressure angle (this family) | designed | gear-* |
| tooth form | 12 DP, 14.5° or 20° (the file name carries the angle); 14.5° and 20° gears do not mesh | 12 DP gear of the same pressure angle | designed | gear-* |

## Sizes

| teeth N | pitch Ø = N / DP, in (mm) | outside Ø = (N + 2) / DP, in (mm) | root Ø 14.5°, in (mm) | root Ø 20°, in (mm) | base Ø 14.5°, in (mm) | base Ø 20°, in (mm) | example face, in | example bore, in |
|---|---|---|---|---|---|---|---|---|
| 12 | 1 (25.40) | 1.1667 (29.63) | 0.8072 (20.50) | 0.7917 (20.11) | 0.9681 (24.59) | 0.9397 (23.87) | 11/16 | 1/4 |
| 14 | 1.1667 (29.63) | 1.3333 (33.87) | 0.9738 (24.74) | 0.9583 (24.34) | 1.1295 (28.69) | 1.0963 (27.85) | 11/16 | 5/16 |
| 16 | 1.3333 (33.87) | 1.5 (38.10) | 1.1405 (28.97) | 1.125 (28.57) | 1.2909 (32.79) | 1.2529 (31.82) | 11/16 | 3/8 |
| 18 | 1.5 (38.10) | 1.6667 (42.33) | 1.3072 (33.20) | 1.2917 (32.81) | 1.4522 (36.89) | 1.4095 (35.80) | 11/16 | 3/8 |
| 20 | 1.6667 (42.33) | 1.8333 (46.57) | 1.4738 (37.44) | 1.4583 (37.04) | 1.6136 (40.98) | 1.5662 (39.78) | 11/16 | 1/2 |
| 24 | 2 (50.80) | 2.1667 (55.03) | 1.8072 (45.90) | 1.7917 (45.51) | 1.9363 (49.18) | 1.8794 (47.74) | 11/16 | 5/8 |
| 28 | 2.3333 (59.27) | 2.5 (63.50) | 2.1405 (54.37) | 2.125 (53.97) | 2.259 (57.38) | 2.1926 (55.69) | 11/16 | 5/8 |
| 30 | 2.5 (63.50) | 2.6667 (67.73) | 2.3072 (58.60) | 2.2917 (58.21) | 2.4204 (61.48) | 2.3492 (59.67) | 11/16 | 3/4 |
| 32 | 2.6667 (67.73) | 2.8333 (71.97) | 2.4738 (62.84) | 2.4583 (62.44) | 2.5817 (65.58) | 2.5058 (63.65) | 11/16 | 3/4 |
| 36 | 3 (76.20) | 3.1667 (80.43) | 2.8072 (71.30) | 2.7917 (70.91) | 2.9044 (73.77) | 2.8191 (71.60) | 11/16 | 3/4 |
| 40 | 3.3333 (84.67) | 3.5 (88.90) | 3.1405 (79.77) | 3.125 (79.38) | 3.2272 (81.97) | 3.1323 (79.56) | 11/16 | 1 |
| 48 | 4 (101.60) | 4.1667 (105.83) | 3.8072 (96.70) | 3.7917 (96.31) | 3.8726 (98.36) | 3.7588 (95.47) | 11/16 | 1 |
| 60 | 5 (127.00) | 5.1667 (131.23) | 4.8072 (122.10) | 4.7917 (121.71) | 4.8407 (122.95) | 4.6985 (119.34) | 11/16 | 1 |

## Where the files are

- Martin Sprocket & Gear: [G-85 spur gear data: PD = N / DP, OD = (N + 2) / DP, a = 1 / DP, ht = 2.157 / DP, t = 1.5708 / DP](https://martinsprocket.com/docs//partinterchange/g-85.pdf) — web — Publisher's page; dimensions are facts
- Engineers Edge: [Gear design equations: 20 degree full-depth teeth (ANSI B6.1): PD, OD, a = 1/P, b = 1.25/P, ht = 2.25/P, centre distance](https://engineersedge.com/gear_formula.htm) — web — Publisher's page; dimensions are facts
- Machinery's Handbook, 31st ed. (online edition): [Spur gearing: 14.5 degree full-depth tooth proportions (a = 1/P, b = 1.157/P, ht = 2.157/P)](https://online.flippingbook.com/view/954046886/872) — web — Publisher's page; dimensions are facts
- Machinery's Handbook, 31st ed. (online edition): [Table 4: tooth proportions for fine-pitch involute spur and helical gears of 14.5, 20 and 25 degrees (ANSI B6.7): b = 1.2/P + 0.002, ht = 2.2/P + 0.002](https://online.flippingbook.com/view/954046886/870) — web — Publisher's page; dimensions are facts
- Machinery's Handbook, 31st ed. (online edition): [Spur gearing: outside and root diameter formulas, 20 degree fine-pitch full-depth teeth (20 P and finer)](https://online.flippingbook.com/view/954046886/873) — web — Publisher's page; dimensions are facts
- Applied Industrial (Boston Gear): [Boston Gear 16 DP 14.5 degree 14-tooth steel spur gear: PD 0.875 in, OD 1 in, face 0.5 in, bore 0.375 in](https://www.applied.com/c-brands/c-regal-rexnord/c-boston-gear/nb14b-3-8/16-DP-14-5-PA-14-Teeths-Steel-Spur-Gear/p/101752354) — web — Publisher's page; dimensions are facts
- SDP/SI: [48 DP inch spur gears (catalogue pages list the tooth counts and bores; CAD per part on each product page)](https://shop.sdp-si.com/s1084z-048a040.html) — web — Publisher's page; dimensions are facts
- SDP/SI: [Inch pitch spur gear catalogue sheet](https://shop.sdp-si.com/media/pdf/81001085.pdf) — web — Publisher's page; dimensions are facts

## Free STEP/STL (26 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/spur-gears-dp-12/index.json

- gear-dp12-14-5pa-12t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-12t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-12t.stl) — 12 DP spur gear, 12 teeth, 14.5° pressure angle: pitch Ø25.400 mm (1 in), outside Ø29.633 mm (1.1667 in), root Ø20.502 mm; face 17.46 mm (11/16 in) and bore Ø6.350 mm (1/4 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-20pa-12t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-12t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-12t.stl) — 12 DP spur gear, 12 teeth, 20° pressure angle: pitch Ø25.400 mm (1 in), outside Ø29.633 mm (1.1667 in), root Ø20.108 mm; face 17.46 mm (11/16 in) and bore Ø6.350 mm (1/4 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-14-5pa-14t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-14t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-14t.stl) — 12 DP spur gear, 14 teeth, 14.5° pressure angle: pitch Ø29.633 mm (1.1667 in), outside Ø33.867 mm (1.3333 in), root Ø24.735 mm; face 17.46 mm (11/16 in) and bore Ø7.938 mm (5/16 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-20pa-14t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-14t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-14t.stl) — 12 DP spur gear, 14 teeth, 20° pressure angle: pitch Ø29.633 mm (1.1667 in), outside Ø33.867 mm (1.3333 in), root Ø24.342 mm; face 17.46 mm (11/16 in) and bore Ø7.938 mm (5/16 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-14-5pa-16t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-16t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-16t.stl) — 12 DP spur gear, 16 teeth, 14.5° pressure angle: pitch Ø33.867 mm (1.3333 in), outside Ø38.100 mm (1.5 in), root Ø28.969 mm; face 17.46 mm (11/16 in) and bore Ø9.525 mm (3/8 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-20pa-16t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-16t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-16t.stl) — 12 DP spur gear, 16 teeth, 20° pressure angle: pitch Ø33.867 mm (1.3333 in), outside Ø38.100 mm (1.5 in), root Ø28.575 mm; face 17.46 mm (11/16 in) and bore Ø9.525 mm (3/8 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-14-5pa-18t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-18t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-18t.stl) — 12 DP spur gear, 18 teeth, 14.5° pressure angle: pitch Ø38.100 mm (1.5 in), outside Ø42.333 mm (1.6667 in), root Ø33.202 mm; face 17.46 mm (11/16 in) and bore Ø9.525 mm (3/8 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-20pa-18t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-18t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-18t.stl) — 12 DP spur gear, 18 teeth, 20° pressure angle: pitch Ø38.100 mm (1.5 in), outside Ø42.333 mm (1.6667 in), root Ø32.808 mm; face 17.46 mm (11/16 in) and bore Ø9.525 mm (3/8 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-14-5pa-20t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-20t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-20t.stl) — 12 DP spur gear, 20 teeth, 14.5° pressure angle: pitch Ø42.333 mm (1.6667 in), outside Ø46.567 mm (1.8333 in), root Ø37.435 mm; face 17.46 mm (11/16 in) and bore Ø12.700 mm (1/2 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-20pa-20t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-20t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-20t.stl) — 12 DP spur gear, 20 teeth, 20° pressure angle: pitch Ø42.333 mm (1.6667 in), outside Ø46.567 mm (1.8333 in), root Ø37.042 mm; face 17.46 mm (11/16 in) and bore Ø12.700 mm (1/2 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-14-5pa-24t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-24t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-24t.stl) — 12 DP spur gear, 24 teeth, 14.5° pressure angle: pitch Ø50.800 mm (2 in), outside Ø55.033 mm (2.1667 in), root Ø45.902 mm; face 17.46 mm (11/16 in) and bore Ø15.875 mm (5/8 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-20pa-24t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-24t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-24t.stl) — 12 DP spur gear, 24 teeth, 20° pressure angle: pitch Ø50.800 mm (2 in), outside Ø55.033 mm (2.1667 in), root Ø45.508 mm; face 17.46 mm (11/16 in) and bore Ø15.875 mm (5/8 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-14-5pa-28t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-28t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-28t.stl) — 12 DP spur gear, 28 teeth, 14.5° pressure angle: pitch Ø59.267 mm (2.3333 in), outside Ø63.500 mm (2.5 in), root Ø54.369 mm; face 17.46 mm (11/16 in) and bore Ø15.875 mm (5/8 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-20pa-28t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-28t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-28t.stl) — 12 DP spur gear, 28 teeth, 20° pressure angle: pitch Ø59.267 mm (2.3333 in), outside Ø63.500 mm (2.5 in), root Ø53.975 mm; face 17.46 mm (11/16 in) and bore Ø15.875 mm (5/8 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-14-5pa-30t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-30t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-30t.stl) — 12 DP spur gear, 30 teeth, 14.5° pressure angle: pitch Ø63.500 mm (2.5 in), outside Ø67.733 mm (2.6667 in), root Ø58.602 mm; face 17.46 mm (11/16 in) and bore Ø19.050 mm (3/4 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-20pa-30t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-30t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-30t.stl) — 12 DP spur gear, 30 teeth, 20° pressure angle: pitch Ø63.500 mm (2.5 in), outside Ø67.733 mm (2.6667 in), root Ø58.208 mm; face 17.46 mm (11/16 in) and bore Ø19.050 mm (3/4 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-14-5pa-32t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-32t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-32t.stl) — 12 DP spur gear, 32 teeth, 14.5° pressure angle: pitch Ø67.733 mm (2.6667 in), outside Ø71.967 mm (2.8333 in), root Ø62.835 mm; face 17.46 mm (11/16 in) and bore Ø19.050 mm (3/4 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-20pa-32t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-32t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-32t.stl) — 12 DP spur gear, 32 teeth, 20° pressure angle: pitch Ø67.733 mm (2.6667 in), outside Ø71.967 mm (2.8333 in), root Ø62.442 mm; face 17.46 mm (11/16 in) and bore Ø19.050 mm (3/4 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-14-5pa-36t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-36t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-36t.stl) — 12 DP spur gear, 36 teeth, 14.5° pressure angle: pitch Ø76.200 mm (3 in), outside Ø80.433 mm (3.1667 in), root Ø71.302 mm; face 17.46 mm (11/16 in) and bore Ø19.050 mm (3/4 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-20pa-36t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-36t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-36t.stl) — 12 DP spur gear, 36 teeth, 20° pressure angle: pitch Ø76.200 mm (3 in), outside Ø80.433 mm (3.1667 in), root Ø70.908 mm; face 17.46 mm (11/16 in) and bore Ø19.050 mm (3/4 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-14-5pa-40t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-40t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-40t.stl) — 12 DP spur gear, 40 teeth, 14.5° pressure angle: pitch Ø84.667 mm (3.3333 in), outside Ø88.900 mm (3.5 in), root Ø79.769 mm; face 17.46 mm (11/16 in) and bore Ø25.400 mm (1 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-20pa-40t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-40t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-40t.stl) — 12 DP spur gear, 40 teeth, 20° pressure angle: pitch Ø84.667 mm (3.3333 in), outside Ø88.900 mm (3.5 in), root Ø79.375 mm; face 17.46 mm (11/16 in) and bore Ø25.400 mm (1 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-14-5pa-48t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-48t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-48t.stl) — 12 DP spur gear, 48 teeth, 14.5° pressure angle: pitch Ø101.600 mm (4 in), outside Ø105.833 mm (4.1667 in), root Ø96.702 mm; face 17.46 mm (11/16 in) and bore Ø25.400 mm (1 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-20pa-48t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-48t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-48t.stl) — 12 DP spur gear, 48 teeth, 20° pressure angle: pitch Ø101.600 mm (4 in), outside Ø105.833 mm (4.1667 in), root Ø96.308 mm; face 17.46 mm (11/16 in) and bore Ø25.400 mm (1 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-14-5pa-60t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-60t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-14-5pa-60t.stl) — 12 DP spur gear, 60 teeth, 14.5° pressure angle: pitch Ø127.000 mm (5 in), outside Ø131.233 mm (5.1667 in), root Ø122.102 mm; face 17.46 mm (11/16 in) and bore Ø25.400 mm (1 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet
- gear-dp12-20pa-60t: [STEP](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-60t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-dp-12/gear-dp12-20pa-60t.stl) — 12 DP spur gear, 60 teeth, 20° pressure angle: pitch Ø127.000 mm (5 in), outside Ø131.233 mm (5.1667 in), root Ø121.708 mm; face 17.46 mm (11/16 in) and bore Ø25.400 mm (1 in) are examples, the tooth form is the standard's; true involute flanks, no hub, keyway, chamfer or root fillet

## Questions

**What is the pitch diameter of a 12 DP, 20 tooth gear?**

1.6667 in (42.333 mm); outside diameter 1.8333 in (46.567 mm).

**What is the tooth depth of a 12 DP gear?**

Whole depth 2.25 / 12 = 0.1875 in for 20°, 2.157 / 12 = 0.1797 in for 14.5° (minimum values).

**What is the centre distance of two 12 DP gears, 20 and 40 teeth?**

(20 + 40) / (2 × 12) = 2.5000 in (63.500 mm).

## Fits with

- [Spur gears, 16 diametral pitch (DP): 12 to 60 teeth, 14.5° and 20° involute, pitch / outside / root diameter and STEP/STL](https://xemstudio.com/objects/spur-gears-dp-16/)
- [Spur gears, 20 diametral pitch (DP): 12 to 60 teeth, 14.5° and 20° involute, pitch / outside / root diameter and STEP/STL](https://xemstudio.com/objects/spur-gears-dp-20/)
- [Spur gears, 24 diametral pitch (DP): 12 to 60 teeth, 14.5° and 20° involute, pitch / outside / root diameter and STEP/STL](https://xemstudio.com/objects/spur-gears-dp-24/)
- [Spur gears, module 1: 10 to 80 teeth (20° involute)](https://xemstudio.com/objects/spur-gears-module-1/)
- [Spur gears, involute 20°: module 0.5, 1 and 2, 12–60 teeth](https://xemstudio.com/objects/spur-gears-involute/)
- [Gear racks ISO 53 module 1 to 3: tooth profile, pitch, depth and root radius + module 1.5, 2.5, 3 rack STEP/STL](https://xemstudio.com/objects/gear-racks-iso-53-module-1-to-3/)