Ceiling Fan Size Calculator

The short answer

Size the fan by the room’s floor area: 29 to 36 in up to 75 sq ft, 36 to 42 in up to 144 sq ft, 44 in up to 225 sq ft and 50 to 54 in up to 400 sq ft. Hang it so the blades sit at least 7 ft above the floor, 8 to 9 ft if the ceiling allows, and keep the blade tips 18 in from the walls. For the downrod, subtract 9 ft from the ceiling height: 36 in under a 12 ft ceiling.

How to measure

1. Measure the room wall to wall in both directions, so the calculator can work out the floor area and check the shorter side.
2. Measure the ceiling height where the fan will hang, from the floor to the ceiling.
3. Note any light kit: it hangs below the blades, so the fan needs a shorter downrod.
4. On the product page, look for the blade span (the diameter the blades sweep) and the height from the ceiling to the blades.

How to use the calculator

1. Enter the room’s width and length and the ceiling height.
2. Tick the light kit box if the fan has one.
3. Read the result: the blade span to look for, the mount or downrod, about how high the blades will sit and how the common blade spans fit your room.
4. Save or share it. Copy link keeps your numbers in the address.

How we calculate

Your fan’s own instructions come first. The spans, heights and clearances below cover the rest.

• Blade span: by floor area, 29 to 36 in up to 75 sq ft, 36 to 42 in up to 144 sq ft, 44 in up to 225 sq ft and 50 to 54 in up to 400 sq ft. Over 400 sq ft, 54 to 72 in or more than one fan. A room on a band’s edge belongs to the smaller band. A span Fits inside the room’s band and is Tight when it’s larger but still within a wider range for the same area: 44 to 54 in for rooms over 144 sq ft and up to 225 sq ft, for example.
• Walls: the blade tips stay at least 18 in from every wall, so no fan wider than the room’s shorter side minus twice that.
• Downrod: the ceiling height minus 9 ft, which puts the blades about 8 ft above the floor, allowing about 12 in for the fan itself. With a light kit, 12 in shorter. Downrods come in 6 in steps, so we round down, up to 120 in. When the result is shorter than one step, the short rod that comes with the fan does the job.
• Low ceilings: when even the short rod would bring the blades below 7 ft, the answer is a hugger fan, mounted flush, whose blades sit no more than 10 in below the ceiling, or less under a very low ceiling.
• Two fans: in a room longer than 18 ft or larger than 400 sq ft, we size each fan for half the floor area.

Worked examples

Worked example

A 12 × 15 ft bedroom with a 9 ft ceiling

What we know

• Room: 12 × 15 ft
• Ceiling: 9 ft
• Light kit: no

How it works out

1. Floor area: 12 × 15 ft = 180 sq ft.
2. Blade span for rooms up to 225 sq ft: 44 in.
3. Walls: the blade tips need 18 in from each wall, so up to 108 in fits across the 12 ft side.

A 12 × 15 ft room (180 sq ft) takes a fan with a 44 in blade span. Under a 9 ft ceiling, the short rod that comes with the fan puts the blades about 7 ft 8 in above the floor.

Worked example

A 10 × 10 ft home office with an 8 ft ceiling

What we know

• Room: 10 × 10 ft
• Ceiling: 8 ft
• Light kit: no

How it works out

1. Floor area: 10 × 10 ft = 100 sq ft.
2. Blade span for rooms up to 144 sq ft: 36 to 42 in.
3. Walls: the blade tips need 18 in from each wall, so up to 84 in fits across the 10 ft side.

A 10 × 10 ft room (100 sq ft) takes a fan with a 36 to 42 in blade span. Under an 8 ft ceiling, choose a hugger (flush mount) fan whose blades sit no more than 10 in below the ceiling, so they stay 7 ft above the floor.

Worked example

A 16 × 20 ft living room with a 12 ft ceiling

What we know

• Room: 16 × 20 ft
• Ceiling: 12 ft
• Light kit: no

How it works out

1. Floor area: 16 × 20 ft = 320 sq ft.
2. Blade span for rooms up to 400 sq ft: 50 to 54 in.
3. Walls: the blade tips need 18 in from each wall, so up to 156 in fits across the 16 ft side.
4. Downrod: 12 ft − 9 ft = 36 in.

A 16 × 20 ft room (320 sq ft) takes a fan with a 50 to 54 in blade span. Under a 12 ft ceiling, use a 36 in downrod to bring the blades to about 8 ft above the floor. In a room this size, two fans spread the air better: one in each half, each about 44 in.

Ceiling fan size chart

The blade span for each floor area, with a room of that size as an example.

Downrod length chart

The downrod for common ceiling heights, without and with a light kit, for blades about 8 ft above the floor.

Before you buy

Fans differ in how far their blades sit below the ceiling. The product page or the manual gives that height, and it’s the number to check against your ceiling before you order a downrod.

A sloped ceiling may need a longer downrod so the blades clear the slope, and a steep one needs an angled mounting kit; the fan’s instructions give the angle its standard bracket handles.