Electricity Bill Estimator

Add the appliances in your home with their wattage and how long they run each day, and this estimates what each one costs per month and per year. The output is ranked by annual cost, because that ordering is usually a surprise and it is the only one that tells you where to act.

How to use it

1. Enter the rate you pay per kilowatt-hour, taken from your electricity bill.
2. Add appliances from the preset list, or add your own and type the wattage.
3. Set how many hours a day each one actually runs, and how many of them you have.
4. Read the ranked chart. The item at the top is costing you the most per year.
5. Change the hours on that item to see what a real reduction would be worth.

Your list is saved in your browser, so it is still there when you come back.

Watts are not the bill. Watt-hours are

The single most useful correction to how people think about electricity: wattage tells you how fast an appliance draws power, not how much it costs. Cost depends on wattage multiplied by time, and time varies by two orders of magnitude across a house.

Compare a kettle with a set-top box. The kettle is rated 2200W — one of the highest figures in the kitchen — and boiling water for a household takes maybe twelve minutes a day in total. That is 2200 × 0.2 hours = 440 watt-hours, or 0.44 kWh per day. At 17 cents that is about $27 a year.

The set-top box draws 25W, which sounds trivial. But it is never switched off, so it runs 24 hours a day: 25 × 24 = 600 watt-hours, or 0.6 kWh. That is about $37 a year — more than the kettle, from an appliance drawing one eighty-eighth of the power.

Scale that up and the pattern becomes the whole story of a bill. A tumble dryer at 3000W is genuinely expensive because it runs for long cycles. An electric heater at 1500W left on for four winter evenings a week costs more than every light in the house combined. Meanwhile the appliances people worry about — the kettle, the microwave, the toaster — barely register, because they run for minutes.

This is why the ranking here is by annual cost and not by wattage, and why the tool explicitly points out when the appliance drawing the most power is not the one costing the most money. That mismatch is the normal case, not the exception.

The corollary is that standby power matters more than its size suggests. Ten devices drawing 5W each while “off” is 50W continuously, which is 438 kWh a year, or roughly $75. Nothing about that is visible from a wattage label.

What it does not do

It assumes an appliance draws its rated wattage for the hours you specify, which overstates anything thermostatically controlled. A fridge is plugged in for 24 hours but its compressor runs perhaps a third of the time, so enter effective running hours rather than hours plugged in — the preset uses 8 for exactly this reason. Standing charges, tiered tariffs, time-of-use rates and taxes are not modelled. Preset wattages are typical values and your own appliances will differ, sometimes considerably.

Nothing is uploaded. The list lives in your browser’s local storage and nowhere else.

Typical appliance wattages

Appliance	Watts	Typical hours/day
Tumble dryer	3000	0.7
Electric oven	2400	0.5
Kettle	2200	0.2
Washing machine	900	0.8
Air conditioner (window)	1200	6
Electric heater	1500	4
Dishwasher	1800	1
Desktop computer	200	8
Fridge freezer	150	8 (cycling)
Television, 55-inch LED	110	5
Games console	150	3
Laptop	60	8
Set-top box	25	24
Router	10	24
LED bulb	9	5

What one kWh a day costs per year

Rate per kWh	Cost per year
$0.10	$36.50
$0.15	$54.75
$0.17	$62.05
$0.20	$73.00
$0.25	$91.25
$0.30	$109.50