Electricity Cost Calculator
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Our electricity calculator helps you calculate the power usage of your electrical devices and work out how much they are costing you per day, week, month and year. You may wish to know how you can carry out these calculations yourself, using a formula. So, in our article below we look at how to calculate electricity costs and discuss some ideas for how you can reduce your electricity bill.
On this page:How to calculate electricity usage and cost
To manually calculate the amount of electricity your appliance consumes, you can use a formula. Multiply the appliance's wattage by the number of hours you use it each day, then divide the result by 1000 to calculate the daily consumption in kilowatt-hours (kWh).
Where:
- E = energy in kWh/day
- P = power in watts (W)
- t = hours used per day
To calculate the cost, you can then multiply the result by your electricity cost per kWh. We'll look at how to do this part in a minute. Note that you can check your figures using our electricity cost calculator at the top of the page.
Example
Let's say you have a 900W toaster that you use for 10 minutes per day. Your equation will look like this:
E = 900 × (10/60) / 1000 = 0.15
Your toaster will therefore be using 0.15 kWh per day.
How much is my appliance costing me?
Energy bills use Kilowatt-hours (kWh), whereby each unit means using one kilowatt of energy for an hour. The price per kWh varies by location, supplier and tariff.
Under some tariffs, electricity costs more per unit during peak hours – usually around midday – while off-peak energy is less expensive. You will find the price(s) per unit on the supplier's bill, contract or quotation.
Example cost calculation
Let's go back to our toaster example from above. To calculate the cost of powering our toaster, we multiply the 0.15 kWh-per-day figure by our energy cost per kWh. For our example, we'll say that our electricity provider charges us $0.20 (20 cents) per kWh.
0.15 × $0.20 = $0.03
So, we've calculated that the toaster is costing you 3 cents per day in electricity. To work out the yearly cost, we can multiply the figure by 365. This gives an annual electricity cost of $11.
As an alternative calculation, you can work out the kW figure (there are 1000W in 1 kW) and then multiply that by the electricity cost per kWh and then by the amount of time as a percentage of an hour. Here's the Money Saving Expert founder Martin Lewis's explanation of this (UK):
Watt does it cost to turn on electricals? A rough rule of thumb courtesy of last night's @itvMLshow #MartinLewis #energy #energybills@ pic.twitter.com/4cNM8wTX8T
— Martin Lewis (@MartinSLewis) October 19, 2022
Quick note on electric vehicles (EVs): We've built a separate MPGe Calculator to help you work out miles/kWh and MPGe energy consumption and cost calculation for your EV.
Electricity cost calculations for common household appliances
Let's consider some more example calculations for common household appliances. We'll continue to assume electricity costs $0.20 per unit or kWh.
If we use a kettle, portable heater or dishwasher rated at 1.5KW for one hour per day it would cost: 1500W/h x 1 / 1000 x $0.20 = 30c per day. That works out at $9.90 monthly.
Five 10W LED light bulbs switched on for six hours a day in winter would cost: 5 x 10 W/h x 6 / 1000 x $0.20 = 6 cents per day, or $1.80 monthly.
Adding the power used by all the appliances we use will give us an idea of the total energy cost.
What are the most power-consuming home appliances?
In terms of wattage, the most power-hungry appliances include:
- EV chargers (typically from 7KW to 12KW).
- Clothes dryers (approximately 4KW).
- Air conditioning units (between 600 Watts and 4KW, depending on the cycle).
- Ovens (2KW).
Looking at overall electricity consumption, which takes into account the amount of usage as well as the power of each item, home improvement expert Bob Vila says that the most energy-sucking appliances in homes are:
- Fridges
- Water heaters
- Clothes washers and dryers
- Lights
- Dehumidifiers
- Hot tubs
- Devices left in standby mode
- Televisions and game consoles
Energy saving tips
With the rising cost of energy, you may be wondering how you can reduce the amount of electricity you're using. So, let's take a look at that.
The EnergySage website gives fifteen tips to help conserve energy and cut down your electricity bill. These include using smart power strips (and turning them off when appliances aren't in use), washing your clothes in cold water and switching to energy-efficient lighting, which uses as little as a tenth of the electricity of conventional bulbs.
The Money Saving Expert website (UK) features an excellent article with a range of tips, from not running your dishwasher half empty to minimising the use of appliances that use a lot of power (clothes dryers, ovens, etc.) to using a microwave or air fryer for cooking simple food items instead of your oven. They give an example:
Energy efficiency site Sust-it tested a 2000-watt air fryer against a standard oven with no fan and a 900-watt microwave by cooking a single jacket potato. While the microwave was cheapest (with a eight-minute cooking time, costing just 7p), the air fryer proved quicker and cheaper than an oven, cooking the potato in 60 minutes at a cost of 27p, compared with 70 minutes in the oven for 37p.
Another increasingly popular idea that you may wish to consider is using a dehumidifier for drying wet clothes, instead of switching your heating on or running a clothes dryer.
I hope this article has been helpful for calculating the usage cost of your electrical items and for giving you some ideas and resources for how to cut down on your electricity use.
Calculator by Alastair Hazell Updated: January 16, 2024References
- Estimating Appliance and Home Electronic Energy Use. Energy.gov.
- Home Appliances: Amps And Watts Ratings. Electrical Safety First.
- List of the Power Consumption of Typical Household Appliances. DaftLogic.
If you have any problems using our electricity cost calculator, please contact us.