What size ceiling fan do you need?

What size ceiling fan do I need?

ENERGY STAR matches the blade span to the room: up to 75 square feet, 29–36 inches; 76–144 square feet, 36–42 inches; 144–225 square feet, 44 inches; 225–400 square feet, 50–54 inches. A 12 × 10 ft bedroom is 120 square feet, so a 36–42 inch fan.

What about a room over 400 square feet?

The ENERGY STAR chart stops at 400 square feet. For a larger or long, narrow room, consider two fans, each sized for its half of the room, so the air reaches all of it.

How high should a ceiling fan hang?

ENERGY STAR says to install a fan in the middle of the room, at least 7 feet above the floor and 18 inches from the walls, and that 8 to 9 feet above the floor gives the best airflow.

What length downrod do I need?

A standard mount uses a 3–5 inch downrod. On higher ceilings, extended downrods bring the blades down to the 8–9 ft range — ENERGY STAR lists them from 6 inches for a 9 ft ceiling up to 120 inches for a 20 ft ceiling. The calculator shows how far below your ceiling the blades should sit.

How is a ceiling fan measured?

By its blade span: the diameter of the circle the blade tips sweep. For a fan with an odd number of blades, measure from the center to one blade tip and double it.

Which fan size applies when the room is exactly on a boundary?

The ENERGY STAR chart lists 75, 144, 225 and 400 square feet as the upper limits of each row. A 12 × 12 ft room is exactly 144 square feet, so it falls in the 76–144 row (36–42 inches), not in the next one.

Can I use a low-profile fan in a room with an 8 foot ceiling?

The ENERGY STAR guidance asks for the blades to be at least 7 feet above the floor. On an 8 foot ceiling that leaves at most 12 inches between the ceiling and the lowest part of the blades, so a flush or low-profile mount is the usual choice. Check the product's specifications for its blade height.

How the calculation works

The calculator multiplies the room's length by its width to get the area in square feet and looks it up in the ENERGY STAR chart for the blade span. The span is the diameter of the circle swept by the blade tips. The chart gives a range for each area: a room up to 75 square feet suits a fan 29 to 36 inches across; 76 to 144 square feet, 36 to 42 inches; 145 to 225 square feet, 44 inches; and 226 to 400 square feet, 50 to 54 inches. The chart stops at 400 square feet. The mounting height follows the same guidance: at least 7 feet above the floor and 18 inches from the walls, with 8 to 9 feet best for airflow.

Worked examples

a 9 × 8 ft nursery (72 square feet): 29–36 inches; a 12 × 12 ft bedroom (144 square feet): 36–42 inches; a 15 × 15 ft living room (225 square feet): 44 inches; an 18 × 20 ft family room (360 square feet): 50–54 inches; a 20 × 24 ft great room (480 square feet): beyond the chart. A room of up to 400 square feet is the largest the chart covers. Beyond that, such as the 480 square foot great room, ENERGY STAR advice for a larger or long, narrow room is two fans, each sized for its half of the room. For a 9 foot ceiling, ENERGY STAR lists a 6 inch downrod to bring the blades into the 8 to 9 foot range.

Common mistakes

• Measuring the room including closets and alcoves. Use the space the fan actually has to move air in, and not storage areas that open into it.
• Using one big fan for a long, narrow room. The chart works from area, but the air has to reach the whole room. For a long room, two fans may serve it better.
• Confusing blade span with the fixture width. The span is measured tip to tip, not the width of the motor housing.

Sources and related calculators

Sizing chart and mounting heights: ENERGY STAR, "Ceiling Fan Basics" and the ENERGY STAR guidance for ceiling fans. Related: BTU calculator, CFM calculator and attic ventilation calculator.