Fan Power Calculator
Brake horsepower and running cost of a fan.
Enter your values
Enter the airflow in CFM.
Enter the static pressure in in w.c..
Enter the fan efficiency in %.
Enter the run hours per year in h.
Enter the electricity rate in $/kWh.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Brake horsepower
- 0.484 hp
- Input power
- 0.401 kW
- Annual energy
- 1,203 kWh
- Annual cost
- $192.53
- Watts per CFM
- 0.201
Quick answer
Fan brake horsepower equals CFM times static pressure divided by 6356 times the fan efficiency.
BHP = CFM x SP / (6356 x efficiency)
At a glance
| What it does | Brake horsepower and running cost of a fan. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Airflow, Static pressure, Fan efficiency, Run hours per year, Electricity rate |
| Main output | Brake horsepower |
| Formula | BHP = CFM x SP / (6356 x efficiency) |
| Cost | Free — no sign-up, no download |
How to use the Fan Power Calculator
- 1Enter airflow and the static pressure the fan works against.
- 2Use the fan's efficiency from its curve, typically 55–70%.
- 3Add run hours and your electricity rate to see the annual cost.
Inputs explained
- Airflow(CFM)
- Enter the airflow in CFM.
- Static pressure(in w.c.)
- Enter the static pressure in in w.c..
- Fan efficiency(%)
- Enter the fan efficiency in %.
- Run hours per year(h)
- Enter the run hours per year in h.
- Electricity rate($/kWh)
- Enter the electricity rate in $/kWh.
Worked example
Using the values the calculator loads with:
Inputs
- Airflow2000 CFM
- Static pressure1.0 in w.c.
- Fan efficiency65 %
- Run hours per year3000 h
- Electricity rate0.16 $/kWh
Results
- Brake horsepower0.484 hp
- Input power0.401 kW
- Annual energy1,203 kWh
- Annual cost$192.53
- Watts per CFM0.201
Frequently asked questions
What is a good watts per CFM?
Efficient residential ventilation runs under 0.4 W/CFM; poor systems exceed 1.0.
Why include motor efficiency?
Brake horsepower is shaft power; the motor draws more from the wall, typically 10–15% extra.
What do I need to enter into the Fan Power Calculator?
Just 5 values: airflow, static pressure, fan efficiency, run hours per year, electricity rate. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Fan Power Calculator work out the answer?
Fan brake horsepower equals CFM times static pressure divided by 6356 times the fan efficiency. It applies the formula BHP = CFM x SP / (6356 x efficiency) and shows the working so you can check each step by hand.
Is the Fan Power Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.