How much electricity does an extractor fan use? Get your own answer: enter your wattage, hours of use per day and electricity rate, and press Calculate to see your cost per day, month and year. Those same results also cover extractor fan power consumption.
You probably expect a humming fan above the shower to add something noticeable to your bill, so how much electricity does an extractor fan use is a fair question. The short answer is very little: a typical bathroom extractor fan costs about a dollar or two per year, and this guide shows you the exact sum so you can check your own unit.
Almost every extractor fan is a small motor pushing moisture-laden room air outdoors, and small motors are cheap to feed. Most units draw somewhere between 10 and 40 watts while they run. A fan with a built-in heater is the exception, because the heating element can pull more than a thousand watts on its own.
The wattage printed on the fan's label or in its manual is the single most useful number you can find. Quiet, high-airflow models sit near the top of the usual range, while a basic ceiling unit sits near the bottom. If the label lists several speeds, use the highest figure to stay on the cautious side.
Your supplier does not bill in watts. It bills in kWh, one kilowatt-hour being a device drawing one thousand watts for a full hour. A 17-watt fan would need to run for roughly 59 hours before it used a single unit, which is why it hardly registers beside an oven or a tumble dryer.
You do not need a special tool to calculate the cost of one fan. The formula has three steps, and the first two use numbers you can read straight off the label and your bill. If you only know the typical hours per day, multiply that figure by the days in the period you care about, such as 30 for a month. Related: power bank electricity consumption.
$$\text{Cost} = \frac{\text{Watts}}{1000} \times \text{Hours} \times \text{Rate}$$Divide the fan's rating by 1,000 to turn watts into kilowatts. A 17-watt unit becomes 0.017 kW. This is only a unit change, nothing else about the fan is altered.
Next, multiply the kilowatts by your usage hours, then by the price you pay. Your electricity rate is on every statement, usually quoted in cents per kWh. Convert it to dollars before you multiply, so 16.4 cents becomes $0.164. Rates differ a lot between regions and suppliers, so check your own electricity rates rather than a national average.
Say your fan is rated at 17 watts, it runs for 45 minutes each day, and you pay $0.164 for every unit. That is 0.017 kW for 0.75 hours, giving 0.01275 kWh each day. Multiply by the price and the daily cost is about 0.21 cents. The table below shows what that does over longer periods.
| Period | Energy used | Cost at $0.164 |
|---|---|---|
| Daily | 0.013 kWh | $0.002 |
| Monthly (30 days) | 0.38 kWh | $0.06 |
| Yearly (365 days) | 4.65 kWh | $0.76 |
| Non-stop, all year | 148.9 kWh | $24.42 |
Your monthly cost works out to roughly six cents and the annual cost under a dollar, while leaving the fan on around the clock would still be only about $24.42 per year. Running one continuously is wasteful, but it is not ruinous.
Try swapping in your own figures. Change the rating to match your label, change the minutes to match how long your household showers, and change the price to match your latest statement. Because every input is a straight multiplier, doubling any one of them doubles the answer, so you can estimate a new scenario in your head without redoing the whole sum.
Whether extractor fans expensive to run is even the right worry depends on the model. Using the same 45 minutes a day and the same $0.164 price, here is how different ratings compare. You can also check how many watts does a garbage disposal use.
| Fan type | Rating | Yearly energy | Yearly cost |
|---|---|---|---|
| Basic ceiling unit | 8 W | 2.2 kWh | $0.36 |
| Standard bathroom unit | 17 W | 4.7 kWh | $0.76 |
| High-airflow kitchen unit | 75 W | 20.5 kWh | $3.37 |
| Heated unit, heater on | 1,100 W | 301.1 kWh | $49.38 |
A standard unit costs well under a dollar, and even the 75-watt kitchen model stays in the low single digits. Only the heater changes the picture, which is the next thing to understand.
The motor is the cheap part. If your unit includes a heater, that element can draw hundreds of times more than the motor, so the same 45 minutes costs about $49 across a year when the heat is switched on. Use the heater sparingly, or check whether the fan can run with the heat off.
A 60-watt incandescent light bulb draws more than three times as much as a 17-watt fan, so leaving one light on during a shower costs more than the fan clearing the steam. That comparison puts fan power consumption in perspective: it is among the smallest loads in a household, a genuinely low energy appliance next to a kettle or a dryer.
The rating sets the ceiling, but a few other factors decide how much energy use actually shows up on your electricity bill. Three of them matter most.
The usage frequency of a fan in a busy family bathroom is far higher than in a spare room, and every extra hour adds to the total. Because the cost scales directly with time, halving the time the fan runs halves the cost.
A properly installed fan vents outdoors through short, sealed ductwork. A long, kinked or leaking duct makes the motor work harder and leaves moist air behind, so you run the unit longer to get the same result. Dust and mould on the blades have a similar effect.
In a cold or humid climate, steam lingers longer and the fan needs more minutes to clear it. A small, windowless bathrooms layout also keeps steam trapped, so those rooms rely on the fan more than a bathroom with a window.
The savings here are small in dollars, but the habits are free. These steps keep consumption low without letting dampness build up. You can also check how much energy does a led light bulb use.
A timer switches the fan off after a set delay, and a humidity sensor does it once the room dries out. Either removes the risk of a fan left running all night, so it can save money over time even though it adds a small upfront cost.
When you replace a fan, compare the energy rating and airflow rather than only the price. A more energy-efficient unit moves the same air using a lower-wattage motor, and a good energy efficiency figure is a quiet sign of better build quality overall.
It also helps to maintain regularly any filter or cover, since these small jobs prevent the slow decline in airflow that makes fans run for longer.
Run the fan for about 30 minutes after a shower so that moisture leaves the room rather than settling on cold surfaces. That window works for most bathrooms; larger rooms or cold weather call for a little longer, and a hot, dry day can allow less.
The cost of those extra minutes is tiny. With the 17-watt example, every additional 15 minutes a day adds about $0.25 over a year, while leaving moisture behind invites mould (also spelled mold) and damp patches that cost far more to repair. For tenants who cannot change the fan itself, switching it on early and leaving it on briefly is the best compromise.
Where possible, use that routine alongside opening a window when the weather allows. Combine a short run with good humidity control and you protect the building, keep the air fresh and keep energy spending to a few cents. Efficient ventilation and a low bill are not in conflict.
In practice, the electricity used by an extractor fan is tiny: a rating of 10 to 40 watts, a daily run of half an hour to an hour and a normal unit price add up to a few dollars at most. If a heater is built in, check that first, because it will be the real cost. For everything else, the best efficiency gain is simply not leaving the fan on when the room is dry.