How do you calculate electricity cost?

Multiply watts by hours and divide by 1,000 to get kWh, then multiply by your rate. A 1,500 W heater for 5 hours is 7.5 kWh — about $1.13 at $0.15/kWh.

How do I find an appliance's wattage?

It's on the label near the serial number. If only amps and volts are listed, multiply them: 5 A × 120 V = 600 W.

Why does my appliance cost less than calculated?

Anything with a thermostat cycles on and off. A 1,500 W heater might only run 40% of the time, so estimate the hours it's actually heating rather than the hours it's switched on.

Does leaving a charger plugged in cost much?

Almost nothing. A charger draws about 5 W, well under a dollar a year. The real costs are appliances that make or move heat — dryers, heaters, water heaters and air conditioning.

Electricity Bill Calculator – Appliance Running Cost

The Appliance

Power Rating

On the label or in the manual. Multiply amps × volts if you only have those.

Hours Used Per Day

Days Used Per Month

Yearly cost is this × 12. For something that runs every single day, use 30.4 — the average month is longer than 30 days.

Your Electricity Rate

$per kWh

Take this from your own bill — rates vary hugely by country, state and tariff

How Many Of Them

Results

Enter your details to see results

Cost Per Month

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kWh Per Day

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kWh Per Month

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Cost Per Day

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Cost Per Year

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Cost Per Hour

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kWh Per Year

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How We Calculated

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Electricity Bill Calculator Guide

Work out what any appliance actually costs to run, from its wattage and your own electricity rate.

The Formula

kWh = watts × hours ÷ 1,000
Cost = kWh × your rate
A 1,500 W heater for 5 hours is 7.5 kWh. At $0.15/kWh that's $1.13 a day, about $34 a month.

Where to Find Your Numbers

Wattage is on the appliance label, usually near the serial number. If it only lists amps and volts, multiply them — 5 A × 120 V = 600 W.

Your rate is on your bill, expressed per kWh. Use your real one. Rates differ by a factor of three or more between regions, and a national average would make this calculator useless for you specifically.

Watts Are Not the Whole Story

The label shows maximum draw, and plenty of appliances don't sit at maximum.

Anything with a thermostat — fridges, heaters, ovens, air conditioners — cycles on and off. A 1,500 W heater in a warm room might run 40% of the time and cost 40% of what this says. For those, estimate the hours it's actually heating, not the hours it's switched on. A plug-in energy monitor settles the question properly for about the price of a takeaway.

The Appliances That Actually Cost Money

People obsess over phone chargers and ignore the real spenders. What matters is watts × hours, and the winners are almost always the things that make heat or move it: heating and air conditioning, electric water heaters, tumble dryers, ovens.

A phone charger is about 5 W. Left plugged in all year it costs well under a dollar. A tumble dryer is 3,000 W and costs more in ten loads than the charger does in a decade.

Standby Is Real But Small

Devices in standby draw 1–5 W each. Individually trivial; across 30 devices it's perhaps 60 W constant, which is roughly 525 kWh a year — around $79 at $0.15. Worth switching off the worst offenders, not worth losing sleep over.

If Your Tariff Has Time-of-Use Rates

Many bills now charge different rates by time of day, and this calculator uses one flat rate. If you're on a time-of-use tariff, run it twice with your peak and off-peak rates to see the spread — that gap is exactly what makes running the dishwasher at midnight worth it.

Related: EV charging cost calculator.

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