Fan Static Pressure Calculator
System resistance a fan must overcome.
Enter your values
Enter the duct loss in in w.c..
Enter the filter loss in in w.c..
Enter the coil loss in in w.c..
Enter the grilles and registers in in w.c..
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.
- Total static pressure
- 0.68 in w.c.
- In pascals
- 169
- Largest component
- duct
- Select fan at
- design CFM against 0.68 in w.c.
Quick answer
A fan must be selected at the system's total static pressure, not in free air, or delivered airflow falls short.
TSP = duct loss + filter + coil + grilles
At a glance
| What it does | System resistance a fan must overcome. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Duct loss, Filter loss, Coil loss, Grilles and registers |
| Main output | Total static pressure |
| Formula | TSP = duct loss + filter + coil + grilles |
| Cost | Free — no sign-up, no download |
How to use the Fan Static Pressure Calculator
- 1Enter each component's pressure drop at design airflow.
- 2Use a dirty-filter value, not a clean one, so the system still works months later.
- 3Select the fan from its curve at the total static shown.
Inputs explained
- Duct loss(in w.c.)
- Enter the duct loss in in w.c..
- Filter loss(in w.c.)
- Enter the filter loss in in w.c..
- Coil loss(in w.c.)
- Enter the coil loss in in w.c..
- Grilles and registers(in w.c.)
- Enter the grilles and registers in in w.c..
Worked example
Using the values the calculator loads with:
Inputs
- Duct loss0.25 in w.c.
- Filter loss0.15 in w.c.
- Coil loss0.2 in w.c.
- Grilles and registers0.08 in w.c.
Results
- Total static pressure0.68 in w.c.
- In pascals169
- Largest componentduct
- Select fan atdesign CFM against 0.68 in w.c.
Frequently asked questions
Why does free-air CFM mislead?
Fan ratings in free air ignore the system; a 400 CFM fan may deliver 250 CFM once ducted.
What is a typical residential total?
Around 0.5 in w.c. is the design target for a standard air handler.
What do I need to enter into the Fan Static Pressure Calculator?
Just 4 values: duct loss, filter loss, coil loss, grilles and registers. 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 Pressure Calculator work out the answer?
A fan must be selected at the system's total static pressure, not in free air, or delivered airflow falls short. It applies the formula TSP = duct loss + filter + coil + grilles and shows the working so you can check each step by hand.
Is the Fan Static Pressure 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.