Are bathroom extractor fans expensive to run?

Written by

26 March 2024


5 min read

Bathroom extractor fans are crucial for maintaining a fresh, moisture-free bathroom, ensuring the air we breathe in these intimate spaces remains healthy and clean. Naturally, achieving these objectives requires regular use of the fans, leading to the inevitable question: are they expensive to operate?

In this guide, we'll address this concern by providing approximate figures for running a bathroom extractor fan, along with a straightforward formula you can use to estimate the running costs of your fan.

To calculate the cost of running a bathroom extractor fan in Australia, you can use the following formula:

Cost=Power Consumption (kW)×Usage Hours×Electricity Rate (AUD/kWh)

Here’s how to use the formula:

Step one: calculate power consumption (kW)

To calculate the power consumption of your fan you need to convert the fan's power consumption from watts to kilowatts. Since 1 kW equals 1,000 watts, you can do this by dividing the fan's wattage by 1,000. For example, if your fan uses 20 watts, that's 0.02 kW.

Step two: usage hours 

Estimate how many hours per day you use the fan. Multiply this by the number of days you're calculating for (e.g.30 days for a monthly cost).

Step three: find out your electricity rate (AUD/kWh)

This step involves finding out the cost of electricity per kilowatt-hour in your area. This varies by location and provider but is typically expressed in cents. You might see rates like 25 cents per kWh, which you should convert to dollars for this calculation ($0.25/kWh).

Step four: calculating the estimated cost

After gathering the necessary information from the previous steps, you're now ready to calculate the estimated cost of running your bathroom extractor fan. Use the following formula: Estimated Cost=Power Consumption (kW)×Usage Hours×Electricity Rate (AUD/kWh)

Example calculation:

Let's assume your fan has a power consumption of 20 watts (0.02 kW after conversion), you use the fan for 2 hours every day, and your electricity rate is $0.25 per kWh. The calculation would be as follows:

Estimated Cost=0.02 kW×2 hours×0.25 AUD/kWh

This formula gives you the daily cost of running your fan. To find the monthly cost, multiply the daily cost by the number of days in your billing period (e.g.30 days).

Bathroom extractor fans are often tucked away, pretty much out of sight.
Bathroom extractor fans are often tucked away, pretty much out of sight.

The amount a bathroom extractor fans costs to run comes down to a few key factors:

Power consumption (watts)

This measures the amount of electricity a fan uses. Fans with higher wattage consume more electricity, leading to higher operating costs. Most bathroom extractor fans have wattage ratings that range from 5 to 30 watts.

Usage frequency and duration

This factor is relatively self-explanatory; usage frequency refers to how often the fan is used, and duration refers to how long it runs each time.

Electricity rate in your area

Electricity rates in Australia vary between 23.67 to 45.54c/kWh. Here's a breakdown state by state:

ACT - 23.67c/kWh

NSW - 33.84 c/kWh

NT - 27.37c/kWh

QLD - 30.21c/kWh

SA - 45.54c/kWh

TAS - 28.12c/kWh

VIC - 28.52c/kWh

WA - 30.05c/kWh

The efficiency of the the fan

Some fans are more energy-efficient than others, using less electricity to achieve the same level of ventilation. Choosing a fan with a higher energy rating can lead to long-term savings.

Correct installation 

Naturally, a fan that’s properly installed will work more efficiently than one that isn't. For example, a fan that is not venting air correctly may need to run longer to effectively reduce moisture.


Bathroom extractor fans need to be properly maintained in order to run effectively. Fans that are clogged with dust or debris, or older extractor fans have to work harder leading to higher running costs. 

A new bathroom fan is an essential part of any new bathroom.
A new bathroom fan is an essential part of any new bathroom.
A bathroom extractor fan is also sometimes known as an a bathroom exhaust fan.
A bathroom extractor fan is also sometimes known as an a bathroom exhaust fan.

Running a bathroom extractor fan is relatively low cost and you’ll typically not need to run one for extended periods each day. However, there are still steps you can take to ensure you keep running costs as low as possible:

Opt for energy-efficient models

If you’re purchasing a new fan, look for energy-efficient models that provide the same level of ventilation using less power. These models might have a higher upfront cost but will save money in the long run due to lower operating costs.

Use timers or humidity sensors

Installing a timer or a humidity sensor can significantly reduce the time your fan runs, thereby saving electricity. A timer can automatically turn off the fan after a set period, while a humidity sensor can do so once the air returns to an acceptable moisture level.

Maintain regularly

Ensure your fan is cleaned and maintained regularly. As we mentioned earlier, dust and debris can reduce efficiency, causing the fan to work harder and use more energy to achieve the same result.

Proper installation

A correctly installed fan operates more efficiently. Make sure that the fan vents to the outside directly in the shortest possible route and that the ducting is properly sealed. This ensures that moist air is effectively removed with minimal energy use.

Adjust usage according to need

Operate the fan only when necessary, such as during and shortly after showers or baths when humidity levels are highest. Avoid leaving it on continuously to prevent unnecessary energy consumption.

Educate household members

Ensure all members of your household understand the importance of turning off the fan when it's not needed. 

Explore alternative ventilation methods

On cooler days, consider natural ventilation methods, such as opening a window, to help reduce moisture. This can be a free and energy-efficient way to supplement your fan’s work.

As you can see, it's relatively straightforward to estimate the cost of running a bathroom extractor fan. Simply follow the formula laid out in this article, and you'll be good to go.

At ArchiPro we recognise and acknowledge the existing, original and ancient connection Aboriginal and Torres Strait Islander peoples have to the lands and waterways across the Australian continent. We pay our respects to the elders past and present. We commit to working together to build a prosperous and inclusive Australia.