Belt Length Calculator - Free Online V-Belt & Timing Belt Tool
Belt Length Calculator
Calculate belt length, center distance, and tension for V-belt and timing belt drives. Essential tool for power transmission system design.
Calculation Mode
Pulley Configuration
Belt Type & Conditions
Belt Drive Guidelines
Minimum Pulley Sizes
- • V-Belt A/B: 75/125 mm
- • V-Belt C/D: 200/355 mm
- • Timing 8mm pitch: 24 teeth
- • Poly-V J section: 50 mm
Speed Limits
- • V-Belt: 30 m/s max
- • Timing Belt: 40 m/s max
- • Flat Belt: 100 m/s max
- • Min arc contact: 120°
How to use this calculator
🔗 How to Use This Calculator
- Select calculation mode (belt length or center distance)
- Enter driver and driven pulley diameters
- Input center distance OR belt length
- Select belt type (V-belt, timing, etc.)
- Add operating conditions for tension analysis
- Calculate to find results and standard sizes
📐 Belt Length Formula
Exact Belt Length
L = 2C·cos(α) + π(D+d)/2 + α(D-d)
Where:
α = sin⁻¹[(D-d)/(2C)]
C = Center distance
D = Large pulley diameter
d = Small pulley diameter
Contact Angles
θ₁ = π - 2α (small pulley)
θ₂ = π + 2α (large pulley)
Min recommended: 120°
🌟 Practical Examples
100mm to 250mm pulleys, 500mm centers
Belt length: 1495mm, Contact: 154°
150mm to 450mm pulleys, timing belt
Speed reduction 3:1, 1800mm belt
V-belt drive, 5kW at 1450 RPM
B-section belt, 1270mm standard
💡 Design Tips
- • Ideal center distance: 1-3 × (D+d)/2
- • Minimum wrap angle: 120° (150° preferred)
- • Check belt speed limit for type
- • Allow ±3% adjustment for tensioning
- • Use larger pulleys for longer belt life
- • Match belt and pulley groove profiles
- • Consider temperature derating factors
⚠️ Important Considerations
- • Always use manufacturer's rated power
- • Apply service factors for shock loads
- • Check shaft and bearing loads
- • Ensure proper ventilation for cooling
- • Avoid back-bending on idlers
- • Replace belts in matched sets
- • Never mix belt types or brands
About this calculator
Calculate belt length for two-pulley systems. Find center distance and belt tension for V-belts and timing belts.
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