FAQ / How to Calculate Required V-Belts Size
V-Belt Length & Loading Calculator
Calculate the exact V-belt size you need with our free online calculator. Whether you're an engineer designing a new drive system or a technician replacing a worn belt, this tool provides precise measurements for belt length, speed ratios, wrap angles, and shaft loading—helping you get the right belt the first time.
Simply enter your pulley diameters and center distance, and our calculator handles the rest. Optional fields let you factor in power transmission and friction coefficients for detailed load analysis.
Belt Length & Loading Calculator
How to Use the V-Belt Calculator
Required Fields
Diameter driver pulley (D₁): The diameter of the pulley connected to the motor or input shaft, measured in millimetres.
Diameter driven pulley (D₂): The diameter of the pulley on the output or driven shaft.
Center to center distance: The distance between the centers of both pulleys, measured in millimetres. This determines your belt's datum length.
Optional Fields (for Load Analysis)
Transmitting power (P): The power being transmitted, in kilowatts. Used to calculate drive force and tension loads.
Rotational speed (n₁): The speed of the driver pulley in revolutions per minute (rpm). Needed to calculate belt speed and torque.
Pulley groove angle: The V-groove angle of your pulleys in degrees (typically 34° or 40°). Affects friction and load distribution.
Coefficient of friction (μ): Material friction coefficient between belt and pulley (typically 0.3–0.6). Higher values improve grip and load capacity.
Understanding Your Results
Belt Datum Length (L): The reference length of your belt. Use the correction factor table above to convert to inside length for your specific belt type.
Drive ratio (i): The ratio between pulley sizes. This tells you the speed reduction or increase between input and output shafts.
Belt speed: The linear speed of the belt in metres per second.
Wrap angle: The degrees of pulley circumference the belt contacts.
Tensions and shaft load: Key measurements for ensuring your belt and pulleys can handle the transmitted load.
Shop Our Complete V-Belt Range
Once you've calculated your exact belt size, find it in our extensive stock. We supply all standard V-belt profiles—Z, A, B, C, AX, and BX sections—from leading manufacturers. Fast delivery across the UK and worldwide.
Browse our range of V-Belts here.
