# Spur gears, module 1.25: 10 to 80 teeth (20° involute)

> What is the pitch diameter of a module 1.25 spur gear?

- Category: Hardware › Motion
- Kind: Hardware
- Basis: ISO 53 basic rack: 20° pressure angle, addendum m, dedendum 1.25 m; pitch Ø = m × teeth, tip Ø = m × (teeth + 2), root Ø = m × (teeth − 2.5)
- Page: https://xemstudio.com/objects/spur-gears-module-1-25/ · JSON: https://xemstudio.com/api/geometry?object=spur-gears-module-1-25 · Plain text: https://xemstudio.com/objects/spur-gears-module-1-25/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** True size, with no printing tolerance added.

## Notes

- Centre distance of two module 1.25 gears = m × (N1 + N2) / 2. Face width 10 mm, plain bore (add a hub, key or set screw to suit). Teeth below 17 are drawn without profile shift, so they undercut as real unshifted gears do.

## Sizes

| teeth | pitch_dia_mm | tip_dia_mm | root_dia_mm | face_mm | bore_mm |
|---|---|---|---|---|---|
| 10 | 12.5 | 15.0 | 9.38 | 10.0 | 3 |
| 12 | 15.0 | 17.5 | 11.88 | 10.0 | 4 |
| 14 | 17.5 | 20.0 | 14.38 | 10.0 | 5 |
| 15 | 18.75 | 21.25 | 15.62 | 10.0 | 5 |
| 16 | 20.0 | 22.5 | 16.88 | 10.0 | 6 |
| 18 | 22.5 | 25.0 | 19.38 | 10.0 | 7 |
| 20 | 25.0 | 27.5 | 21.88 | 10.0 | 8 |
| 22 | 27.5 | 30.0 | 24.38 | 10.0 | 9 |
| 24 | 30.0 | 32.5 | 26.88 | 10.0 | 9 |
| 25 | 31.25 | 33.75 | 28.12 | 10.0 | 10 |
| 28 | 35.0 | 37.5 | 31.88 | 10.0 | 11 |
| 30 | 37.5 | 40.0 | 34.38 | 10.0 | 12 |
| 32 | 40.0 | 42.5 | 36.88 | 10.0 | 13 |
| 35 | 43.75 | 46.25 | 40.62 | 10.0 | 14 |
| 36 | 45.0 | 47.5 | 41.88 | 10.0 | 15 |
| 40 | 50.0 | 52.5 | 46.88 | 10.0 | 16 |
| 42 | 52.5 | 55.0 | 49.38 | 10.0 | 17 |
| 45 | 56.25 | 58.75 | 53.12 | 10.0 | 19 |
| 48 | 60.0 | 62.5 | 56.88 | 10.0 | 20 |
| 50 | 62.5 | 65.0 | 59.38 | 10.0 | 21 |
| 56 | 70.0 | 72.5 | 66.88 | 10.0 | 23 |
| 60 | 75.0 | 77.5 | 71.88 | 10.0 | 25 |
| 64 | 80.0 | 82.5 | 76.88 | 10.0 | 25 |
| 70 | 87.5 | 90.0 | 84.38 | 10.0 | 25 |
| 72 | 90.0 | 92.5 | 86.88 | 10.0 | 25 |
| 80 | 100.0 | 102.5 | 96.88 | 10.0 | 25 |

## Where the files are

- ISO: [ISO 53 standard basic rack (20° pressure angle, addendum 1 m, dedendum 1.25 m) and ISO 54 modules](https://www.iso.org/standard/5768.html) — standard — ISO; dimensions are facts (verify at link)

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

Index: https://xemstudio.com/files/hardware/spur-gears-module-1-25/index.json

- gear-m1-25-10t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-10t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-10t.stl) — module 1.25, 10 teeth: pitch Ø12.5, tip Ø15, root Ø9.375, face 10, bore Ø3
- gear-m1-25-12t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-12t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-12t.stl) — module 1.25, 12 teeth: pitch Ø15, tip Ø17.5, root Ø11.875, face 10, bore Ø4
- gear-m1-25-14t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-14t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-14t.stl) — module 1.25, 14 teeth: pitch Ø17.5, tip Ø20, root Ø14.375, face 10, bore Ø5
- gear-m1-25-15t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-15t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-15t.stl) — module 1.25, 15 teeth: pitch Ø18.75, tip Ø21.25, root Ø15.625, face 10, bore Ø5
- gear-m1-25-16t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-16t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-16t.stl) — module 1.25, 16 teeth: pitch Ø20, tip Ø22.5, root Ø16.875, face 10, bore Ø6
- gear-m1-25-18t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-18t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-18t.stl) — module 1.25, 18 teeth: pitch Ø22.5, tip Ø25, root Ø19.375, face 10, bore Ø7
- gear-m1-25-20t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-20t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-20t.stl) — module 1.25, 20 teeth: pitch Ø25, tip Ø27.5, root Ø21.875, face 10, bore Ø8
- gear-m1-25-22t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-22t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-22t.stl) — module 1.25, 22 teeth: pitch Ø27.5, tip Ø30, root Ø24.375, face 10, bore Ø9
- gear-m1-25-24t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-24t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-24t.stl) — module 1.25, 24 teeth: pitch Ø30, tip Ø32.5, root Ø26.875, face 10, bore Ø9
- gear-m1-25-25t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-25t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-25t.stl) — module 1.25, 25 teeth: pitch Ø31.25, tip Ø33.75, root Ø28.125, face 10, bore Ø10
- gear-m1-25-28t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-28t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-28t.stl) — module 1.25, 28 teeth: pitch Ø35, tip Ø37.5, root Ø31.875, face 10, bore Ø11
- gear-m1-25-30t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-30t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-30t.stl) — module 1.25, 30 teeth: pitch Ø37.5, tip Ø40, root Ø34.375, face 10, bore Ø12
- gear-m1-25-32t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-32t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-32t.stl) — module 1.25, 32 teeth: pitch Ø40, tip Ø42.5, root Ø36.875, face 10, bore Ø13
- gear-m1-25-35t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-35t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-35t.stl) — module 1.25, 35 teeth: pitch Ø43.75, tip Ø46.25, root Ø40.625, face 10, bore Ø14
- gear-m1-25-36t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-36t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-36t.stl) — module 1.25, 36 teeth: pitch Ø45, tip Ø47.5, root Ø41.875, face 10, bore Ø15
- gear-m1-25-40t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-40t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-40t.stl) — module 1.25, 40 teeth: pitch Ø50, tip Ø52.5, root Ø46.875, face 10, bore Ø16
- gear-m1-25-42t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-42t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-42t.stl) — module 1.25, 42 teeth: pitch Ø52.5, tip Ø55, root Ø49.375, face 10, bore Ø17
- gear-m1-25-45t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-45t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-45t.stl) — module 1.25, 45 teeth: pitch Ø56.25, tip Ø58.75, root Ø53.125, face 10, bore Ø19
- gear-m1-25-48t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-48t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-48t.stl) — module 1.25, 48 teeth: pitch Ø60, tip Ø62.5, root Ø56.875, face 10, bore Ø20
- gear-m1-25-50t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-50t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-50t.stl) — module 1.25, 50 teeth: pitch Ø62.5, tip Ø65, root Ø59.375, face 10, bore Ø21
- gear-m1-25-56t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-56t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-56t.stl) — module 1.25, 56 teeth: pitch Ø70, tip Ø72.5, root Ø66.875, face 10, bore Ø23
- gear-m1-25-60t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-60t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-60t.stl) — module 1.25, 60 teeth: pitch Ø75, tip Ø77.5, root Ø71.875, face 10, bore Ø25
- gear-m1-25-64t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-64t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-64t.stl) — module 1.25, 64 teeth: pitch Ø80, tip Ø82.5, root Ø76.875, face 10, bore Ø25
- gear-m1-25-70t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-70t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-70t.stl) — module 1.25, 70 teeth: pitch Ø87.5, tip Ø90, root Ø84.375, face 10, bore Ø25
- gear-m1-25-72t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-72t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-72t.stl) — module 1.25, 72 teeth: pitch Ø90, tip Ø92.5, root Ø86.875, face 10, bore Ø25
- gear-m1-25-80t: [STEP](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-80t.step) · [STL](https://xemstudio.com/files/hardware/spur-gears-module-1-25/gear-m1-25-80t.stl) — module 1.25, 80 teeth: pitch Ø100, tip Ø102.5, root Ø96.875, face 10, bore Ø25

## Questions

**Pitch diameter of a module 1.25, 20-tooth gear?**

25 mm; tip 27.5 mm.

**Centre distance?**

m × (N1 + N2) / 2: a 20 and a 40 tooth module 1.25 pair sit 37.5 mm apart.

## Fits with

- [Spur gears, module 0.5: 10 to 80 teeth (20° involute)](https://xemstudio.com/objects/spur-gears-module-0-5/)
- [Spur gears, module 0.8: 10 to 80 teeth (20° involute)](https://xemstudio.com/objects/spur-gears-module-0-8/)
- [Spur gears, module 1: 10 to 80 teeth (20° involute)](https://xemstudio.com/objects/spur-gears-module-1/)
- [Spur gears, module 1.5: 10 to 80 teeth (20° involute)](https://xemstudio.com/objects/spur-gears-module-1-5/)
- [Spur gears, module 2: 10 to 80 teeth (20° involute)](https://xemstudio.com/objects/spur-gears-module-2/)
- [Spur gears, involute 20°: module 0.5, 1 and 2, 12–60 teeth](https://xemstudio.com/objects/spur-gears-involute/)