Choose the largest HVLS fan that fits your roof height and clearances, then divide your floor area by that fan's coverage to get the number of fans. A 24 ft fan covers about 11,688 sq ft, a 20 ft fan about 8,612 sq ft, a 16 ft fan about 7,535 sq ft and a 12 ft fan about 5,382 sq ft.
Step 1: measure the floor you want to cover
Take the length and width of the area where people work or where you want air moving. In a warehouse that may be the whole floor; in a factory it may be the production area only.
Step 2: check the roof height and obstructions
HVLS fans hang from the roof structure, with the blades well above people, racks and vehicles. Note:
- Clear height under the roof steel
- Top of the highest racks
- Overhead cranes and their travel path
- Light fittings, sprinklers, ducts and skylights
Low roofs and many obstructions point to smaller fans. Tall, open buildings suit the largest fans.
Step 3: pick the size
| Fan | Coverage per fan | Speed | Best for |
|---|---|---|---|
| 12 ft | 5,382 sq ft | 90 RPM | Workshops, showrooms, gyms, aisles |
| 16 ft | 7,535 sq ft | 70 RPM | Factory bays, malls, mid-size warehouses |
| 20 ft | 8,612 sq ft | 65 RPM | Large production halls, distribution centres |
| 24 ft | 11,688 sq ft | 60 RPM | Large warehouses, stadiums, exhibition halls |
Step 4: work out the number of fans
Divide the floor area by the coverage per fan and round up.
Example 1: 40,000 sq ft warehouse, high open roof. 40,000 ÷ 11,688 = 3.4, so four 24 ft fans.
Example 2: 18,000 sq ft factory with cranes. Cranes limit the fan size, so use 16 ft fans: 18,000 ÷ 7,535 = 2.4, so three fans placed between crane runs.
Example 3: 6,000 sq ft gym. One 12 ft fan covers about 5,382 sq ft; two give even coverage, or one 16 ft fan if the roof allows.
Our HVLS fan calculator does this for every size at once.
Step 5: place the fans
- Space fans so their air patterns meet rather than overlap heavily
- Keep blades clear of walls, racks and lights
- In racked warehouses, place fans over aisles so air reaches the pickers
- Avoid placing fans directly under skylights or roof vents that can disturb the airflow
Mixing fan sizes
Large buildings often combine sizes: 24 ft fans over open floor and 12 or 16 ft fans in narrower bays, mezzanines or loading areas.
When fans are not enough
HVLS fans make people feel cooler but do not lower the air temperature. In very hot sheds, add industrial duct coolers to bring in cooler fresh air and exhaust fans to remove hot air under the roof.
Get a layout
Send us your drawing with roof height and obstructions marked, and we will place the fans and quote. See HVLS fans for specifications.
Frequently asked questions
How do I calculate how many HVLS fans I need?
Divide the floor area by the coverage of your chosen fan size and round up, then adjust the layout for racks, cranes and lights.
What is the best HVLS fan size for a warehouse?
Usually the 24 ft fan if the roof is high and open, because it covers the most floor per fan; 16 or 20 ft where racks or cranes limit the space.
Can I mix HVLS fan sizes in one building?
Yes. Large buildings often use big fans over open floor and smaller ones in narrow bays.