How much does it cost to leave a fan on all night?

THE scorching hot weather this week might have got you thinking about getting a fan to keep cool. 

Temperatures soared to a sweltering 28C on Thursday ahead of the Bank Holiday weekend, and there could be more hot weather to come this year.

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But if you’re going to be using a fan, you may also be wondering how much the gadgets cost to run.

Energy bills are generally lower during the summer months because there is no need to have the heating on.

But it can still be worth trying to save money on your gas and electricity, starting with knowing how much appliances cost to run.

Here is what you need to know and some other methods that can keep you cool. 

How much energy does a fan use?

First you’ll need to work out how much electricity your fan uses.

You can do this by finding out its “wattage”, which will tell you how much power it uses.

Then you need to find the total output you will have to turn that wattage into kilowatt hours.

You will need to do some maths here.

First, you have to divide the kilowatt hours by 1,000 – that gives you how much output is used in one hour.

So if your fan is 70 watts output on its high setting and you always use this, divide 70 by 1000 = 0.07.

Then you’ll need to multiply this number by the number of hours you’ve used the fan.

For example, if you’re using it for 12 hours at a time, then 0.07kW x 12 hours will mean 0.84kW output.

How much does it cost to leave a fan on all night?

Once you have your kilowatt output, multiply it by the amount you are charged for 1 kW of electricity.

There is no standard price for electricity cost per kWh in the UK, so you’ll need to look at your energy bill to find this amount.

Based on the April 2025 Ofgem price cap, suppliers charge those on the standard variable tariff up to 27.03p per kWh for electricity.

So you’d take your 0.84kW and times it by 27.03p – equalling 22.71p.

The equation is: cost = power (kilowatt) × time (hour) × cost of 1 kWh (pence).

So if your fan costs 22.71p to have on for that long and you have it on for a full week, that adds up to £1.59.

If you repeated that across a month of 4.5 weeks, the cost would be £7.15.

Of course, costs will vary depending on what type of fan you have, how long you’re using it, what setting it’s on and how much you pay for your energy.

Do fans make a room cooler?

The simple answer is no. Although fans can’t make a room cooler, they can make you feel cooler.

Your body temperature will be lowered by the air moving over your skin but a fan won’t do much about the heat inside a room.

That means if you don’t plan on being in the room there’s no point in leaving the fan on.

Fans do not do anything to the heat inside the room itself.

How else can I keep cool in the heat?

If you’re wanting more cost-effective options for keeping cool, here are some more suggestions. 

You could cool your bed sheets down before you sleep by sticking them in the freezer, according to TikTok star That Property Guy.

It’s also worth shutting curtains and blinds during the day as this can help your home stay cool. 

Opening the windows on both sides of your home can create a cooling through-breeze without the cost.

That Property Guy also recommends avoiding using the oven and turning off appliances which are not in use as they release heat too, even on standby.

Tom Church, co-founder of LatestDeals.co.uk, suggests having a cool shower before bed as this can set you up for the night to avoid overheating.

You might not have thought of using hot water bottles to keep you cool, but you could try them in the freezer.

Another option is to use a plastic bottle.

If you want to make your fan work harder, you can put a bowl of with water and ice in front of it to help cool down the house.