Electricity Cost Calculator: Cost to Run Anything

Work out what any appliance costs to run per day, month and year from its wattage, hours of use and your price per kWh.

This calculator turns an appliance's power rating into money. Enter how many watts it draws, how many hours a day you use it and your price per kilowatt-hour, and you get the cost per day, month and year straight away. It is the fastest way to answer "is this thing expensive to run?"

How the math works

Electricity is billed in kilowatt-hours (kWh): one kilowatt (1,000 watts) running for one hour. The formula is simply power (kW) × hours × price. Divide watts by 1,000 to get kilowatts, multiply by the hours you use it, then multiply by your price per kWh.

Worked example: a 1,000 W device used 3 h/day at $0.17/kWh uses 1 kW × 3 h = 3 kWh a day, which costs 3 × $0.17 = $0.51 a day — about $15.52 a month and $186 a year.

Assumptions and limits

This is an estimate for one appliance running at the power you enter. It uses 30.44 days as the average month and 365 days a year. It does not include standby draw when the device is "off", standing charges, taxes, or tiered and time-of-use pricing. For an appliance whose power varies (fridges, ovens, inverter air-con) enter its average or measured consumption rather than the nameplate maximum.

When this calculator helps most

This is the one to reach for whenever you're comparing two options rather than auditing a whole home: deciding whether an old space heater is worth switching off before you leave the room, checking whether upgrading a specific appliance is worth it, or settling an argument about which of two devices is actually driving up the bill. Because it works from wattage and hours rather than a fixed appliance list, it handles anything with a power rating — a hobby kiln, a pond pump, a hairdryer — not just the devices with a dedicated page on this site.

Mistakes that throw off the estimate

The most common one is using the nameplate maximum instead of typical running power. A fridge's compressor cycles rather than running flat out, an oven cycles once it reaches temperature, and many "1,500 W" heaters spend part of their time at a lower thermostat-controlled setting — feeding in the peak label figure for these can overstate the real cost by two or three times. The fix is to use a measured or typical average, which is exactly what the appliance pages on this site already do per device. The second common mistake is forgetting this tool only prices one appliance's active running time — it won't match your bill on its own, because your bill also includes every other appliance, standby draw, and any standing charge or tax that isn't tied to consumption at all.

A quick sanity check on the result

If the yearly figure looks surprisingly large, it's usually because the wattage entered is a peak figure rather than a typical one, or the hours are counting time the appliance is plugged in rather than time it's actually drawing that power. As a rough sense check: under $30/year is typical for small, occasional-use devices (chargers, a router, a lamp); $30–150/year covers most mid-draw appliances used daily (a TV, a desktop PC, a kettle); anything above $150/year usually means a heating or cooling appliance, or a large device running many hours a day. If your result lands well outside the range you'd expect for that kind of device, double-check the wattage first — it's the input most often copied from the wrong place (a max-power spec sheet rather than a running-power measurement).

What it costs in practice

What an appliance costs per year by its power and how many hours a day it runs, at $0.17/kWh.

Your own price and habits change these — the calculator above uses your numbers.

Frequently asked questions