Common Power Transmission Formulas and Conversions
At MDS of Michigan, we often help customers with common power transmission formulas, motor conversions, torque calculations, and speed references. To make things easier, we put together the quick reference table below.
Need help checking a formula? Our team can help with motors, V-belts, sheaves, bearings, chain, sprockets, reducers, and other power transmission parts.
Use the chart below as a general guide for horsepower, kilowatts, torque, speed, weight, length, and other common industrial calculations.
Industrial Unit Conversion Formulas
| Category | Formula | Reverse Formula |
|---|---|---|
| Horsepower / Kilowatts | HP = kW × 1.34 | kW = HP × 0.746 |
| Inches / Millimeters | in = mm ÷ 25.4 | mm = in × 25.4 |
| Pounds / Kilograms | lb = kg × 2.205 | kg = lb × 0.454 |
| Torque Conversion | lb-in = Nm × 8.85 | Nm = lb-in × 0.113 |
| Quarts / Liters | Quart = Liter × 1.057 | Liter = Quart × 0.946 |
Horsepower and Torque Formulas
| Calculation | Formula | Used For |
|---|---|---|
| Horsepower from Torque | HP = T(lb-in) × RPM ÷ 63025 | Finding horsepower when torque is measured in pound-inches. |
| Torque in lb-in | T(lb-in) = HP × 63025 ÷ RPM | Finding torque output from horsepower and RPM. |
| Horsepower from lb-ft Torque | HP = T(lb-ft) × RPM ÷ 5252 | Finding horsepower when torque is measured in pound-feet. |
| Torque in lb-ft | T(lb-ft) = HP × 5252 ÷ RPM | Finding torque in pound-feet from horsepower and RPM. |
Quick tip: When replacing a motor, reducer, or drive component, always confirm horsepower, RPM, torque, frame size, mounting style, and application requirements before ordering.
Conveyor, Lift, and Belt Speed Formulas
| Calculation | Formula | Used For |
|---|---|---|
| Lift Horsepower | HP(lift) = Wgt(lb) × FPM ÷ 33000 × EFF | Estimating horsepower needed to lift a load vertically. |
| Sliding Horsepower | HP(slide) = Wgt(lb) × μ × FPM ÷ 33000 × EFF | Estimating horsepower needed to slide a load across a surface. |
| Belt Speed | FPM = 0.2618 × Dia(in) × RPM | Finding belt speed in feet per minute. |
| Pulley RPM | RPM = FPM × 3.820 ÷ Dia(in) | Finding pulley RPM when belt speed and pulley diameter are known. |
Three Phase Motor Horsepower Formula
| Calculation | Formula | Used For |
|---|---|---|
| 3 Phase Motor HP | HP(3ph) = 1.732 × V × I × PF × EFF ÷ 746 | Estimating three phase motor horsepower using voltage, amperage, power factor, and efficiency. |
Formula note: These formulas are general industry references. Real-world applications may require additional service factors, efficiency losses, safety factors, and manufacturer recommendations.
Need Help With Power Transmission Parts?
MDS of Michigan supplies mechanical, electrical, and power transmission products for industrial applications. Whether you are working with motors, V-belts, sheaves, reducers, bearings, roller chain, sprockets, or couplings, our team can help you find the right part.
Have a Question About a Formula or Part?
Contact MDS of Michigan for help with power transmission calculations, product selection, or replacement parts.
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