If you have ever left an extraction fan running and wondered what it is adding to your electricity bill, the short answer is: very little. Extraction fans are among the lowest-energy appliances in any home or workplace. That said, understanding exactly how much power yours uses, and what drives that cost up or down, helps you make smarter decisions about the equipment you install and how you run it.

How Much Power Does an Extraction Fan Use?

Extraction fans are relatively low-energy devices, typically rated between 6 and 40 watts for domestic models. To put that in perspective, even a 36-watt bathroom fan uses less than half the power of a standard 100-watt light bulb.

Kitchen extraction fans draw more power than bathroom units, typically ranging from 20 to 200 watts depending on the size and type of hood. A conventional kitchen extractor fan can use up to 200 watts when running continuously. Modern energy-efficient trickle fans at the low end can operate on as little as 1 to 2 watts at their baseline speed.

Industrial extraction fans operate at significantly higher wattages, from a few hundred watts for wall-mounted exhaust fans up to several kilowatts for large centrifugal or axial units running continuously in factories, warehouses, and processing facilities.

How to Calculate Your Running Cost

The formula is straightforward:

Cost = (Watts / 1000) x Hours used x Electricity rate (AUD/kWh)

Electricity rates in Australia vary between 23.67 and 45.54 cents per kWh depending on the state. Using a mid-range rate of $0.30 per kWh as a working figure:

A 20-watt bathroom fan running for 2 hours a day costs 0.02 kWh x $0.30 = $0.006 per day, or around $2.19 per year. A 36-watt fan on the same schedule would cost roughly $3.94 per year. Even a 100-watt kitchen exhaust fan running for 1 hour daily would cost around $10.95 per year at that rate.

The costs are modest, but they scale with wattage and runtime. An older, inefficient 200-watt kitchen fan running 5 hours a day represents a meaningfully higher annual cost than a modern low-energy model achieving the same extraction with 30 watts.

What Affects How Much Electricity an Extraction Fan Uses?

Several factors influence the actual electricity draw beyond the rated wattage on the label.

Fan wattage and motor size are the primary drivers. Larger fans moving more air require more powerful motors. Single-speed fans run at full draw whenever they are on, whereas variable-speed models adjust their output and energy use to match actual conditions.

Runtime habits matter significantly. A fan triggered by a light switch that turns off immediately uses far less electricity than one left running for 30 minutes after a shower, but the latter is usually the better ventilation choice. How long the fan runs each session directly multiplies the energy cost.

As bearings wear and fan blades become damaged or dirty, the fan will require more energy to move the same amount of air and may no longer achieve the same level of performance as it once did. An aging or poorly maintained fan can quietly draw more power while delivering less airflow.

Ducting length and restrictions also increase the load on the motor. A fan pushing air through a long, bent duct run works harder than one with a short, clear path to the outside.

Industrial Extraction Fans and Energy Use

At an industrial scale, energy consumption becomes a meaningful operational cost rather than a minor household consideration. Fans running continuously in manufacturing plants, food processing facilities, and warehouses accumulate significant hours, and even a modest reduction in wattage translates into real savings over a year.

Variable speed drives (VSDs) are one of the most effective tools for reducing industrial fan energy use. By modulating fan speed to match actual ventilation demand rather than running at full capacity continuously, VSDs can reduce energy consumption substantially. Demand-controlled ventilation systems take this further by responding to real-time air quality data, running fans harder during high-activity periods and scaling back when spaces are idle. Understanding how industrial ceiling fan energy savings work in practice gives a useful sense of what is achievable through smarter fan selection and control.

Tips to Reduce Running Costs

Upgrading to a modern, energy-efficient model is the single most impactful change for older installations. Contemporary fans achieve equivalent airflow at a fraction of the wattage of units from a decade ago.

Installing a humidistat or timer prevents the fan from running longer than conditions require, cutting unnecessary runtime without compromising ventilation quality. Keeping ducting clear and fan blades clean maintains airflow efficiency so the motor does not have to work harder to compensate for restrictions. Regular servicing also preserves motor performance over time, and a well-maintained fan not only uses less energy but lasts considerably longer. A good overview of maintenance tips for industrial fans covers what to check and how often.

For new installations, choosing a variable-speed model over a single-speed unit gives far more flexibility to match energy use to actual need.

The Bottom Line

Running an extraction fan costs very little. For most domestic installations the annual electricity cost is measured in dollars, not tens of dollars. The greater risk is running the fan too infrequently or turning it off too soon, which leads to mould, dampness, and structural damage that far outweighs any electricity saving. Calculate your own running cost using the formula above, and if your current fan is old or inefficient, the upgrade will likely pay for itself within a few years.