Fan Static Efficiency Calculator
Static efficiency from CFM, static pressure and shaft power.
Enter your values
Enter the airflow in CFM.
Enter the static pressure in in wc.
Enter the measured brake hp in hp.
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.
- Static efficiency
- 52.4%
- Air power (static)
- 3.15 hp
- Rating
- Average
Quick answer
Static efficiency equals CFM times static pressure divided by 6356 times brake horsepower, expressed as a percent.
eff_static = CFM x SP / (6356 x BHP)
At a glance
| What it does | Static efficiency from CFM, static pressure and shaft power. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Airflow, Static pressure, Measured brake HP |
| Main output | Static efficiency |
| Formula | eff_static = CFM x SP / (6356 x BHP) |
| Cost | Free — no sign-up, no download |
How to use the Fan Static Efficiency Calculator
- 1Enter measured CFM, static pressure and brake horsepower from a field test or curve point.
- 2Read the static efficiency and compare it to the manufacturer's peak efficiency point.
- 3Operating far from peak efficiency usually means the fan is oversized or undersized for the job.
Inputs explained
- Airflow(CFM)
- Enter the airflow in CFM.
- Static pressure(in wc)
- Enter the static pressure in in wc.
- Measured brake HP(hp)
- Enter the measured brake hp in hp.
Worked example
Using the values the calculator loads with:
Inputs
- Airflow8000 CFM
- Static pressure2.5 in wc
- Measured brake HP6 hp
Results
- Static efficiency52.4%
- Air power (static)3.15 hp
- RatingAverage
Frequently asked questions
Static vs total efficiency?
Static efficiency ignores velocity pressure recovery, so it is always lower than total efficiency.
What is a good static efficiency?
Well-selected centrifugal fans often reach 65-80% static efficiency near their best efficiency point.
What do I need to enter into the Fan Static Efficiency Calculator?
Just 3 values: airflow, static pressure, measured brake hp. 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 Static Efficiency Calculator work out the answer?
Static efficiency equals CFM times static pressure divided by 6356 times brake horsepower, expressed as a percent. It applies the formula eff_static = CFM x SP / (6356 x BHP) and shows the working so you can check each step by hand.
Is the Fan Static Efficiency 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.