# Timing belt profiles: GT2, HTD 3M / 5M / 8M, T5, T10, AT5, MXL, XL, L, H: pitch, tooth height and pulley pitch diameter

> What is the pitch of a GT2, HTD 3M, 5M, 8M, T5, T10, AT5, MXL, XL or L timing belt, and what is the pitch diameter of a pulley with N teeth?

- Category: Hardware › Bearings, rails & motion
- Kind: Standard part
- Basis: Texas Belting pitch chart for pitch and tooth height, optibelt ISO 5296 numbers for XL / L / H, York Industries for MXL / XL / L pitch; pitch diameter computed as N × pitch / π
- Page: https://xemstudio.com/objects/timing-belt-profiles-pitch-and-tooth/ · JSON: https://xemstudio.com/api/geometry?object=timing-belt-profiles-pitch-and-tooth · Plain text: https://xemstudio.com/objects/timing-belt-profiles-pitch-and-tooth/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
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**Exact dimensions.** True size, with no tolerance added.

## Notes

- Pitch is the distance between belt tooth centres along the pitch line; a pulley with N teeth has pitch Ø = N × pitch / π (a definition, so the last three columns are computed: 20 teeth of 2 mm pitch is 12.73 mm; 20 teeth of 5 mm is 31.83 mm). The pulley's outside diameter is the pitch Ø minus twice the pitch-line differential of the profile; the differentials (for example GT2's 0.254 mm, already on the gt2-pulleys page) were not readable in any table reached for the other profiles, so no OD column is given.
- Table sources: pitch and tooth height of all thirteen profiles come from Texas Belting's pitch chart (a distributor; belt thickness is printed there only for HTD 3M / 5M / 8M). XL, L and H are ISO 5296 profiles and optibelt prints the standard numbers: overall belt thickness hs (2.3, 3.6, 4.0), tooth height ht (1.27, 1.91, 2.29), tooth angle 2β (50°, 40°, 40°), tooth width s (2.57, 4.65, 6.12) and foot / head radii (0.38, 0.51, 1.02). York Industries confirms the MXL, XL and L pitches (0.080, 0.200, 0.375 in).
- Disagreement: H profile tooth height is 2.54 mm (0.100 in) at Texas Belting and 2.29 mm at optibelt; both are shown. XL and L agree (1.27 / 1.91). MXL 2.032 mm is 0.080 in. Other profiles: tooth heights for T2.5, T5, AT5, T10, AT10, GT2 and HTD have one source only.
- Same pitch does not mean same belt: T5 and HTD 5M are both 5 mm pitch but their tooth heights are 1.2 and 2.1 mm, and 2 mm (GT2), 2.5 mm (T2.5) and 3 mm (HTD 3M) belts are listed as separate profiles. ISO 5296 covers the MXL, XL, L, H, XH and XXH profiles (optibelt).
- No tooth-profile files: only XL, L and H have a tooth angle / width / radii here, and the pulley groove (not the belt tooth) is what a drawing needs, which no table read gave. GT2 pulleys with an approximate tooth form are on the gt2-pulleys page and are labelled approximate there.
- Not tabulated: pitch-line differentials, minimum teeth, belt widths per profile (Texas Belting lists a width range per profile), width codes (e.g. 025 = 1/4 in for XL) and pulley flange sizes. Gates / SDP-SI / Misumi / optibelt publish them; none was readable here.

## Sizes

| profile | pitch, mm | pitch, in | tooth height, mm | belt thickness, mm | tooth angle 2β (ISO 5296) | tooth width s, mm | foot / head radius, mm | pitch Ø of 20 teeth, mm | pitch Ø of 30 teeth, mm | pitch Ø of 40 teeth, mm |
|---|---|---|---|---|---|---|---|---|---|---|
| MXL | 2.032 | 0.08 | 0.51 | — | — | — | — | 12.94 | 19.40 | 25.87 |
| GT2 (2 mm) | 2 | 0.0787 | 0.75 | — | — | — | — | 12.73 | 19.10 | 25.46 |
| T2.5 | 2.5 | 0.0984 | 0.7 | — | — | — | — | 15.92 | 23.87 | 31.83 |
| HTD 3M | 3 | 0.1181 | 1.2 | 2.4 | — | — | — | 19.10 | 28.65 | 38.20 |
| T5 | 5 | 0.1969 | 1.2 | — | — | — | — | 31.83 | 47.75 | 63.66 |
| HTD 5M | 5 | 0.1969 | 2.1 | 3.8 | — | — | — | 31.83 | 47.75 | 63.66 |
| AT5 | 5 | 0.1969 | 1.2 | — | — | — | — | 31.83 | 47.75 | 63.66 |
| XL | 5.08 | 0.2 | 1.27 | 2.3 (optibelt) | 50° | 2.57 | 0.38 / 0.38 | 32.34 | 48.51 | 64.68 |
| HTD 8M | 8 | 0.315 | 3.4 | 5.6 | — | — | — | 50.93 | 76.39 | 101.86 |
| L | 9.525 | 0.375 | 1.91 | 3.6 (optibelt) | 40° | 4.65 | 0.51 / 0.51 | 60.64 | 90.96 | 121.28 |
| T10 | 10 | 0.3937 | 2.5 | — | — | — | — | 63.66 | 95.49 | 127.32 |
| AT10 | 10 | 0.3937 | 2.5 | — | — | — | — | 63.66 | 95.49 | 127.32 |
| H | 12.7 | 0.5 | 2.54 (optibelt 2.29) | 4 (optibelt) | 40° | 6.12 | 1.02 / 1.02 | 80.85 | 121.28 | 161.70 |

## Where the files are

- Texas Belting: [Timing belt pitch chart: pitch and tooth height for MXL, GT2, T2.5, 3M, T5, 5M, AT5, XL, 8M, L, T10, AT10, H, 14M, XH, XXH](https://texasbelting.com/pages/timing-belt-pitch-chart) — web — Publisher's page; dimensions are facts
- optibelt: [ZR rubber timing belt drives technical data (ISO 5296): XL / L / H pitch, thickness hs, tooth height ht, tooth angle 2β, tooth width s, radii](https://cdn.shopify.com/s/files/1/0667/2885/3800/files/Optibelt-ZR_Rubber-Timing-Belt-Drives_teknisk_data.pdf) — web — Publisher's page; dimensions are facts
- York Industries: [Synchronous drive specifications: MXL 0.080 in, XL 0.200 in, L 0.375 in pitch](https://www.york-ind.com/engineering/timing-pulleys-tensioners-pulley-stock-and-flanges/synchronous-drive-specifications.html) — web — Publisher's page; dimensions are facts

## Questions

**What is the pitch of GT2, HTD 3M, HTD 5M and HTD 8M belts?**

2 mm, 3 mm, 5 mm and 8 mm. They are named for the pitch in millimetres.

**What is the pitch diameter of a 20 tooth GT2 pulley?**

20 × 2 mm / π = 12.73 mm; the outside diameter is 0.508 mm smaller (gt2-pulleys page).

**Is T5 the same as HTD 5M?**

No: both have 5 mm pitch but different tooth heights (1.2 and 2.1 mm), so they are different profiles.

**What is the pitch of an XL belt?**

0.200 in (5.08 mm); L is 0.375 in (9.525 mm), MXL 0.080 in (2.032 mm), H 0.500 in (12.7 mm).

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