How do I calculate brake horsepower from airflow and static pressure?

Static Pressure Power computes air horsepower as CFM times static pressure in inches of water, divided by 6,356, then divides by fan efficiency to get brake horsepower. For example, 10,000 CFM at 3 inches static with 65 percent efficiency needs about 7.3 BHP. Feed that into Motor Sizing to select the next standard frame up with adequate service factor, since running a motor at its nameplate limit shortens its life.

What impeller balance grade do I need for an industrial fan?

Impeller Balance Tolerance uses the ISO 21940 (formerly ISO 1940) balance grade, commonly G6.3 for general industrial fans and G2.5 for higher-speed or precision units, to compute permissible residual unbalance from rotor mass and operating RPM. Higher speed sharply tightens the allowance because the balance quality relates unbalance to speed. Confirm the result against Vibration Margin so the assembled fan stays under its velocity limit on the test cell.

How do the fan laws affect power when I change speed?

Fan power scales with the cube of speed, so the fan laws matter more than any other relationship here. Airflow CFM changes linearly with RPM, static pressure with the square, and power with the cube. A 10 percent speed increase raises airflow 10 percent but power roughly 33 percent. Use Belt Drive Ratio to set sheave sizes for the target RPM, then recheck Motor Sizing and Static Pressure Power before committing the selection.

How do I estimate the operating energy cost of a blower?

Energy Cost multiplies brake horsepower from Static Pressure Power by 0.746 to get kilowatts, divides by motor efficiency, then applies annual run hours and the electricity rate. A 7.3 BHP fan on a 92 percent efficient motor running 6,000 hours at 0.12 dollars per kWh costs roughly 4,300 dollars a year. This life-cycle figure often outweighs first cost and is a strong point in a Quote Margin discussion with the customer.

How many units can my test cell qualify per shift?

Test Cell Capacity divides available shift time by the per-unit test cycle, which includes mounting, spin-up, the airflow and static pressure sweep, Vibration Margin check, and teardown. A 25-minute cycle yields about 18 units per 8-hour shift per cell. Compare that against Assembly Takt and Throughput Gap to find whether testing, not assembly, is the constraint before you promise a delivery date.

What is the true cost per blower before I quote it?

Cost Per Blower sums the motor, bearings, and purchased components with Sheet Metal Housing Yield for the fabricated housing, Paint Area consumables, Labor Per Unit from Assembly Takt, and a Warranty Risk reserve. Housing material utilization and paint coverage are easy to underestimate on larger units. Roll the total into Quote Margin to hold your markup, and include Energy Cost data to support value-based pricing against a cheaper competitor.

Manufacturing calculator category

Industrial Fans, Blowers & Air Movement Equipment calculators

This category covers the sizing, test, and costing math for industrial fans, blowers, and air movement equipment. It serves application engineers, test cell technicians, and estimators who need to match airflow and static pressure to a motor, balance an impeller, and cost a unit before quoting. Use these calculators to move from a duty point to a buildable, priced machine.

What this hub covers

Free calculators for industrial fan and blower manufacturers, covering airflow CFM, static pressure power, motor sizing, impeller balance, vibration margin, and cost per unit.
Browse industrial fans, blowers & air movement equipment calculators for manufacturing planning, quoting, quality, capacity, and operations decisions.

Best calculators in this category

Airflow CFM: Estimate required fan or blower airflow in CFM from design airflow, correction allowance, and operating time.
Fan Motor Energy Cost: Estimate operating energy cost for a fan or blower from connected motor load, runtime, electricity price, and fan count or test count.
Motor Sizing: Estimate fan motor sizing from airflow, static pressure, a power conversion basis, and service factor.
Impeller Balance Tolerance: Calculate balance tolerance margin by comparing allowable residual unbalance with measured or required residual unbalance.
Noise Risk Score: Score fan noise risk from sound impact, likelihood of exceeding the target, and weakness of current noise controls.
Test Cell Capacity: Estimate good fan or blower test cell output from fans per test cycle, available cycles, test cell uptime, and first-pass test yield.
Sheet Metal Housing Yield: Calculate first-pass sheet metal housing yield from accepted housings, fabricated housings, and target yield.
Energy Cost: Estimate fan or blower energy cost from operating hours, energy cost per hour, operating share, and fixed demand or test charges.
Assembly Takt: Find the takt time for Industrial Fans, Blowers & Air Movement Equipment, the pace, in seconds per unit, that production must hold to exactly meet customer demand.
Cost Per Blower: Estimate cost per blower or fan from build count, loaded cost per unit, included scope, and fixed engineering or test cost.
Fan Efficiency: Calculate fan efficiency attainment from fans meeting efficiency target, fans tested, and the target attainment rate.
Belt Drive Ratio: Estimate fan shaft speed from motor speed, drive ratio, slip or correction basis, and service multiplier.

Common manufacturing problems solved

fans
blowers
air movement
impellers
airflow
cfm
static
pressure
power
motor

Live market signals for this industry

Steel mill PPI stands at 361.439 (BLS, Jun 2026), up 16.9% from a year earlier. New factory orders are up 7.4% year over year (Census).

Category questions

How do I calculate brake horsepower from airflow and static pressure? Static Pressure Power computes air horsepower as CFM times static pressure in inches of water, divided by 6,356, then divides by fan efficiency to get brake horsepower. For example, 10,000 CFM at 3 inches static with 65 percent efficiency needs about 7.3 BHP. Feed that into Motor Sizing to select the next standard frame up with adequate service factor, since running a motor at its nameplate limit shortens its life.
What impeller balance grade do I need for an industrial fan? Impeller Balance Tolerance uses the ISO 21940 (formerly ISO 1940) balance grade, commonly G6.3 for general industrial fans and G2.5 for higher-speed or precision units, to compute permissible residual unbalance from rotor mass and operating RPM. Higher speed sharply tightens the allowance because the balance quality relates unbalance to speed. Confirm the result against Vibration Margin so the assembled fan stays under its velocity limit on the test cell.
How do the fan laws affect power when I change speed? Fan power scales with the cube of speed, so the fan laws matter more than any other relationship here. Airflow CFM changes linearly with RPM, static pressure with the square, and power with the cube. A 10 percent speed increase raises airflow 10 percent but power roughly 33 percent. Use Belt Drive Ratio to set sheave sizes for the target RPM, then recheck Motor Sizing and Static Pressure Power before committing the selection.
How do I estimate the operating energy cost of a blower? Energy Cost multiplies brake horsepower from Static Pressure Power by 0.746 to get kilowatts, divides by motor efficiency, then applies annual run hours and the electricity rate. A 7.3 BHP fan on a 92 percent efficient motor running 6,000 hours at 0.12 dollars per kWh costs roughly 4,300 dollars a year. This life-cycle figure often outweighs first cost and is a strong point in a Quote Margin discussion with the customer.
How many units can my test cell qualify per shift? Test Cell Capacity divides available shift time by the per-unit test cycle, which includes mounting, spin-up, the airflow and static pressure sweep, Vibration Margin check, and teardown. A 25-minute cycle yields about 18 units per 8-hour shift per cell. Compare that against Assembly Takt and Throughput Gap to find whether testing, not assembly, is the constraint before you promise a delivery date.

Last reviewed 2026-05-12.