Industrial Filtration, Separation & Dust Collection calculator
Fan Brake Horsepower Calculator
Calculate fan shaft power at a specified airflow and pressure rise. Use matching total-pressure and efficiency data from the fan curve, plus motor and drive efficiency.
What this calculator does
- Calculate fan shaft power at a specified airflow and pressure rise.
Formula used
- Air horsepower = CFM × Total pressure ÷ 6356
- Brake horsepower = Air horsepower × 100 ÷ Fan efficiency %
- Electrical kW = Brake horsepower × 0.745699872 × 100 ÷ Motor and drive efficiency %
Inputs explained
- Fan Operating Airflow: Actual airflow at the selected fan duty point.
- Fan Total Pressure Rise: Total pressure rise matching the fan efficiency basis.
- Fan Total Efficiency: Total efficiency from the fan curve at this duty.
- Motor and Drive Efficiency: Combined motor and transmission efficiency at operating load.
How to use the result
- Best suited to fan duty checks, electrical load estimates.
- This single duty point does not select a motor or predict surge.
Common questions
- Can I mix static pressure with total efficiency? No. Use pressure and efficiency on the same basis; this tool is labeled for total pressure.
- Is brake horsepower the motor nameplate rating? No. It is the shaft power absorbed at the entered duty point.
- Why is electrical input larger than shaft power? The motor and drive consume energy through losses represented by their combined efficiency.
- Does zero pressure mean the installed fan uses no power? The ideal model returns zero air power. Real idle losses require a measured operating curve.
Last reviewed 2026-10-12.