Calculate Energy Costs

Everyone is concerned about the rising cost of energy, but how can I calculate how much it costs to run and appliance and what can I do to save electricity?

We are charged per unit of electricity, which is measured in kilowatt hours (Kwh), that is a 1000 watt load running for 1 hour. We’ll use an immersion heater as an example, these are typically 3kw or 3000 watts, so if the immersion heater ran for 1 hour it would use 3 units of electricity, in monetary terms it would be 90p per hour if your unit cost was 30p.

An immersion heater is simple to calculate as it would draw 3kw all the time it is on, however an oven for example wouldn’t be consuming its full load all the time it is on, a 2kw oven running for 1 hour may only consume 1kwh because its only heating for 50% of the time.

All appliances should have their rating in watts labelled on them so we can work out what any appliance costs to run, we use the calculation below:

(Appliance rating in watts/1000) x cost per unit of electricity

So let’s look at a 2.4 kw air fryer as an example:


Assuming again a unit of electricity is 30p

we get 

2.4 x 30=72

If we want to work out the cost for an appliance that doesn’t run for an hour exactly, we can use the calculation as follows

(Minutes use/60) x running cost per hour

Using our air fryer for example that runs for 15 mins

(15/60) x 72 =18p

The beauty of an appliance like an air fryer is that they cook very quickly, so a few pork chops cooking for 15 minutes will cost 18p to cook. If we were to cook a joint of pork in a 3kw oven for 2.5 hours, it would typically cost £1.12 assuming the oven is actually heating for 50% of the time. This clearly demonstrates 2 energy saving ideas, firstly cook smaller cuts that cook quickly, secondly unless you’re filling the oven, use an appliance such as an air fryer to reduce the cooking time and cost.

Leave a Comment

Your email address will not be published. Required fields are marked *