Electricity Cost Calculator

Find what any appliance costs to run per day, month and year — and see why the wattage on the label tells you almost nothing on its own.

Reference table

Power	Per month	Per day	Per year
10	$0.31	$0.01	$3.72
25	$0.77	$0.03	$9.31
50	$1.53	$0.05	$18.62
75	$2.30	$0.08	$27.92
100	$3.06	$0.10	$37.23
150	$4.59	$0.15	$55.85
200	$6.12	$0.20	$74.46
250	$7.65	$0.26	$93.08
300	$9.18	$0.31	$111.69
400	$12.24	$0.41	$148.92
500	$15.30	$0.51	$186.15
600	$18.36	$0.61	$223.38
750	$22.95	$0.77	$279.23
1,000	$30.60	$1.02	$372.30
1,500	$45.90	$1.53	$558.45

⚡ Typical Wattages

LED bulb8–12 W
Laptop30–65 W
Fridge100–200 W
Washing machine500 W
Kettle / space heater1,500 W
Tumble dryer3,000 W

The Distinction That Fixes Everything

A watt is a rate, a watt-hour is an amount. A 1,500 W heater for 5 minutes uses the same energy as a 9 W LED bulb for 14 hours — the label alone tells you nothing.
Only kilowatt-hours appear on your bill. Wattage matters only once you multiply it by the hours it actually runs.
Anything that heats is the expensive category: kettles, dryers, heaters and ovens all sit near 1,500–3,000 W. Electronics are rounding errors beside them.
Standby draw is small but constant. A device pulling 3 W all year uses 26 kWh — and a household typically has a dozen of them.

Watts Measure Speed, Not Distance

The wattage printed on an appliance is a rate: how fast it draws energy while it is running. The kilowatt-hour on your bill is a quantity: how much it drew in total. Confusing the two is the reason people are surprised by their bills. A 1,500-watt space heater and a 9-watt LED bulb differ by a factor of 167, but if the heater runs five minutes and the bulb runs fourteen hours, they cost exactly the same. Nothing on either label hints at that, because the label cannot know how long you will leave it on. Multiply the watts by the hours and you get watt-hours — divide by a thousand and you have the only unit your energy supplier actually charges for.

From the Label to the Bill

The whole calculation is watts times hours, divided by a thousand, times your rate. A 1,500-watt heater running six hours a day uses 9,000 watt-hours, or 9 kilowatt-hours, which at 17 cents comes to $1.53 a day — about $46 a month while the weather is cold. Do the same for a 150-watt fridge running continuously and you get 3.6 kWh a day, $0.61, roughly $18 a month, every month of the year. That comparison is the useful one: the heater costs more per month but only for part of the year, while the fridge is a small permanent drain. Anything that produces heat dominates a household bill, and everything else is usually noise.

Standby Power, the Bill You Never See

Devices in standby draw between 0.5 and 10 watts each, continuously, and the total runs to 5–10% of household consumption.
A single device at 3 W uses 26 kWh a year. A house with fifteen of them loses around 400 kWh — a real line on a real bill.
The worst offenders are set-top boxes, games consoles left in rest mode, and older printers.
Chargers with nothing attached draw very little on modern hardware — this one is largely a solved problem.
A plug-in energy meter costs little and settles every argument about which device is actually to blame.
The EU capped standby power at 0.5 W for most new products, so newer equipment is dramatically better than a decade ago.

Getting the Rate Right

Take the price per kWh from your bill, not from a news article. Regional variation within one country is large.
Many bills have a standing daily charge on top of the per-kWh rate. That part does not change with usage, so leave it out of this calculation.
Time-of-use tariffs charge different rates by hour. Running a dryer at 2 a.m. can cost a fraction of the same load at 6 p.m.
Some tariffs are tiered: the rate rises after a monthly threshold, so the last kilowatt-hour costs more than the first.
If you have solar panels, self-consumed energy is worth your import rate, not your export rate — usually a large difference.
Rates move. Anything you calculate today is worth re-checking whenever your tariff changes.

Worked Examples

The obvious one and the invisible one

A 1,500 W heater, 6 hours a day

1,500 × 6 = 9,000 Wh = 9 kWh a day
9 × $0.17 = $1.53 a day
× 30 days = $45.90 a month

$45.90 a month while it's cold

One device on standby at 3 W

3 W × 24 h = 72 Wh a day
× 365 = 26.3 kWh a year
× $0.17 = $4.47 a year, per device

Small alone, ~$60 across a household

Frequently Asked Questions

How do I calculate what an appliance costs to run?

Multiply the watts by the hours it runs, divide by 1,000 to get kilowatt-hours, then multiply by your price per kWh. A 1,500 W heater for 6 hours is 9 kWh, which at 17 cents costs $1.53 a day.

What is the difference between watts and watt-hours?

Watts measure how fast energy is drawn; watt-hours measure how much was drawn. A 1,500 W heater for five minutes uses the same energy as a 9 W bulb for fourteen hours. Only watt-hours — as kilowatt-hours — appear on your bill.

How much does standby power cost?

A device drawing 3 watts continuously uses about 26 kWh a year, roughly $4.50 at 17 cents. That is trivial alone, but a typical household has a dozen or more, and standby is estimated at 5–10% of total domestic consumption.

Which appliances use the most electricity?

Anything that makes heat. Tumble dryers, ovens, kettles, space heaters and electric showers all sit between 1,500 and 3,000 watts. Televisions, laptops and phone chargers are minor by comparison, no matter how long they run.

Where do I find my price per kWh?

On your electricity bill, usually shown as a unit rate. Use that rather than a national average, since regional variation is large. Leave out the standing daily charge — it does not change with how much you use.

Is it cheaper to run appliances at night?

Only on a time-of-use tariff, where rates vary by hour. On a flat tariff the time makes no difference at all. Check which one you are on before rescheduling the laundry.