Pick the right ceiling fan for a room. Enter the room's length, width and ceiling height to get the recommended blade span, the downrod length that puts the blades at the ideal height, the minimum airflow in CFM and whether a large room needs more than one fan.
Last updated:
Room
Units
ft
ft
ft
in
Typical 10–14 in. Used to check the resulting blade height.
Enter your values to see the result.
Advertisement
Advertisement
How to use the Ceiling Fan Size Calculator
Enter the room's length and width in feet or meters.
Enter the ceiling height from floor to ceiling (for a sloped ceiling, the height at the fan location).
Optionally enter the fan body height (motor + mount, about 12 in for most fans) to check the resulting blade height.
Read the blade span, downrod length and CFM to shop for a fan, and check the clearance notes.
How the fan size is chosen
Ceiling fans are sized by room area (length × width). The blade span (tip-to-tip diameter) should grow with the area so the fan can move the whole room's air:
Room area
Example room
Blade span
Up to 75 sq ft
Bathroom, walk-in closet, 8 × 9 ft
29–36 in (74–91 cm)
76–144 sq ft
Bedroom up to 12 × 12 ft
36–42 in (91–107 cm)
145–225 sq ft
Master bedroom, 15 × 15 ft
44–50 in (112–127 cm)
226–400 sq ft
Living room up to 20 × 20 ft
50–54 in (127–137 cm)
Over 400 sq ft
Great room, open plan
56 in+ or several fans
Downrod length and blade height
Blades work best about 7.5 to 9 ft (2.3–2.7 m) above the floor in ordinary rooms, a little higher under tall ceilings, and must never be lower than 7 ft (2.1 m). The calculator uses the standard downrod chart (6 in more per foot of ceiling up to 12 ft, then longer steps) and then checks the blade height:
Blade height = ceiling height − downrod − fan body height
Example: a 10 ft ceiling (120 in) with a 12 in downrod and a 12 in fan body puts the blades at 120 − 12 − 12 = 96 in, exactly 8 ft above the floor. If the result would drop below 7 ft, a shorter downrod or a hugger fan is used instead.
Ceiling height
Downrod
Blade height (12 in body)
8 ft
Flush / hugger
~7 ft
9 ft
6 in
7.5 ft
10 ft
12 in
8 ft
11 ft
18 in
8.5 ft
12 ft
24 in
9 ft
13 ft
36 in
9 ft
14 ft
48 in
9 ft
16 ft
60 in
10 ft
18 ft
72 in
11 ft
Placement tips
Keep blade tips at least 18 in (46 cm) from walls, cabinets and sloped ceilings.
Mount to a ceiling box rated for fan support, not a standard light-fixture box.
For sloped ceilings, use an angled mount kit and a downrod long enough for blade clearance.
Compare airflow efficiency (CFM per watt) on the EnergyGuide-style label when choosing between fans of the same size.
Frequently asked questions
What size ceiling fan do I need?
Match the blade span to the room area: up to 75 sq ft use 29 to 36 inches, 76 to 144 sq ft use 36 to 42 inches, 145 to 225 sq ft use 44 to 50 inches, 226 to 400 sq ft use 50 to 54 inches, and above 400 sq ft use a 56 inch or larger fan or two fans. A 12 × 12 ft room (144 sq ft) suits a 36 to 42 inch fan; a 15 × 15 ft room (225 sq ft) a 44 to 50 inch fan.
How long should the downrod be?
Aim for the blades to sit roughly 7.5 to 9 feet above the floor, a bit higher in very tall rooms. A common guide is no downrod (flush or hugger mount) for 8 ft ceilings, 6 in for 9 ft, 12 in for 10 ft, 18 in for 11 ft, 24 in for 12 ft, 36 in for 13 ft, 48 in for 14 ft and 60 in for 15 ft and above. Many fans include a short 3 to 6 inch downrod in the box.
How low can a ceiling fan hang?
The US National Electrical Code and most manufacturers require the blades to be at least 7 feet above the floor. Blades should also be at least 18 inches from walls and sloped ceilings, and ideally about 10 inches below the ceiling for good airflow.
How much airflow (CFM) should a ceiling fan have?
More CFM means more cooling breeze. As a general guide, look for at least about 2,000 CFM in small rooms, 3,000 to 4,000 CFM in medium bedrooms, around 5,000 CFM in large living rooms and 6,000 CFM or more in great rooms. Compare fans at the same speed setting and check the efficiency in CFM per watt.
When do I need two ceiling fans?
Use two or more fans when the room is larger than about 400 sq ft and long rather than square, or when one fan cannot be centered within about 9 feet of every seating area. Space fans so each covers a roughly square zone.
Which way should a ceiling fan spin?
In summer, run it counterclockwise (looking up) to push air down for a cooling breeze. In winter, reverse it to clockwise on low speed to pull air up and push warm air from the ceiling down along the walls without a draft.
Is my data saved?
Only in your own browser for convenience. Nothing is uploaded.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.