Free Engineering Tool #089
Timing Belt Calculator
Calculate timing belt length in pitches and number of teeth. Supports HTD 3/5/8/14 and GT2/GT3/GT5 profiles. Enter pulley teeth, center distance, and pitch.
Results
Pitch Diameter
Belt Length (Number of Teeth)
Timing Belt Pitch Selection
| Pitch | Profile | Power Range | Min Pulley Teeth |
|---|---|---|---|
| 2 mm | GT2 | Light duty, 3D printers | 12 |
| 3 mm | HTD-3M / GT3 | Up to 5 kW | 12 |
| 5 mm | HTD-5M / GT5 | 2 – 30 kW | 14 |
| 8 mm | HTD-8M | 10 – 100 kW | 22 |
| 14 mm | HTD-14M | 50 – 250+ kW | 28 |
Given: z₁=20, z₂=60, pitch=5 mm, C=200 mm
d₁ = 20×5/π = 31.83 mm, d₂ = 60×5/π = 95.49 mm
L_mm = 2×200 + π(31.83+95.49)/2 + (95.49-31.83)²/(4×200) = 400 + 200.0 + 5.1 = 605.1 mm
Belt teeth = 605.1/5 = 121.0 → nearest whole tooth: 121 teeth (605 mm belt) — check the manufacturer catalogue for the closest available standard length, then re-check the actual center distance
Calculate belt pitch length using L = 2C + π(d₁+d₂)/2 + (d₂−d₁)²/(4C), where d = z×p/π. Divide by pitch and round to the nearest standard belt size (usually even number of teeth).
HTD uses a curvilinear tooth profile. GT (GT2/GT3/GT5) is improved with better load distribution, less backlash, and higher power capacity. GT profiles are recommended for new designs.
GT2 (2mm) for light duty/3D printers, 3M/GT3 for small drives up to ~5 kW, 5M/GT5 for 2–30 kW, 8M for 10–100 kW, 14M for 50–250+ kW.
GT2/3M: 12 teeth, 5M: 14 teeth, 8M: 22 teeth, 14M: 28 teeth. Fewer teeth increases belt bending stress and reduces life.
Timing belts are not elastic — center distance must match belt length exactly. Use a tensioner idler or select pulleys/belt length that give the desired center distance.
The procedures described on this page were developed and field-tested by the Vibromera team using the Balanset-1A, a portable dual-channel balancer and vibration analyzer for on-site rotor balancing.
Professional field balancing instruments. Used in 50+ countries.
Nikolai Shelkovenko
Nikolai Shelkovenko is a vibration analysis engineer and the founder and CEO of Vibromera. For more than 15 years he has balanced rotating equipment in the field rather than on a test bench: mulchers, industrial fans, crushers, centrifuges, shafts and spindles. That work is what the Balanset instruments grew out of — they were designed as a tool a specialist can carry to the machine and use alone, on site, not as laboratory equipment. Vibromera was founded in 2017 and has been based in Porto, Portugal, since 2023. Development, assembly and support of the Balanset line all happen here. The flagship instrument is the Balanset-1A, a portable analyser for single- and two-plane balancing and for vibration diagnostics. Nikolai is personally involved in customer support, in working through difficult balancing cases and in the development of the software. He works with customers worldwide, in any language.
