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Electricity Cost Calculator

Work out how much a single appliance or your whole electricity bill costs — kWh usage, day/night rates, standing charge and CO2 footprint.

✓ Last reviewed: Sources: URE — Komunikat o zatwierdzeniu taryf na 2026 r.

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Sets the currency, available price presets and the CO2 footprint estimate.

Fills the power below with a typical wattage — you can still edit it by hand.

Rated power of the appliance, from its label or manual.

How many hours a day the appliance runs (decimals allowed, e.g. 0.5).

US Dollar

Enter the price you actually pay (gross). To enter a net price instead, fill in VAT/tax below and leave this as net.

Advanced options

Price breakdown (net, VAT, excise)

Optional: fill this in only if the price above is NET (excluding tax) — e.g. Poland 23%, Spain 21%, UK 5%. Leave empty if your price is already gross.

Optional: a tax applied before VAT, so VAT ends up taxing the tax too — e.g. Spain's IEE ≈5.11269632%. Leave empty if not applicable.

US Dollar

Optional: any other flat charge per kWh not covered above (e.g. renewables surcharge, distribution).

Multi-zone tariff (day/night)

Standing charge

US Dollar

Enter the amount straight from your bill, GROSS (tax already included) — it is not affected by the VAT/excise fields above.

Custom billing period

Optional: use this if your bill covers a period other than a calendar month (e.g. you moved house mid-month).

Cyclical use (not daily)

Optional: for appliances used a few times a week rather than daily (e.g. laundry) — overrides hours/day above.

How long a single use lasts.

Your result

Fill in the fields above to see your result.

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What the electricity cost calculator measures

The core formula behind every electricity bill is short: cost = (power in watts ÷ 1000) × hours used × number of days × price per kWh. This electricity cost calculator does that math for you, and it covers two different questions at once.

You can work out the cost of running a single appliance — a fridge, a space heater, an air conditioner, a phone charger — just from its power rating and how many hours a day it runs. Or you can start from a meter reading or a bill: enter your usage in kWh for a month or a year, and the calculator converts it into a daily, monthly and yearly cost. Both paths land on the same set of results: cost per day, month and year, usage in kWh, and — for Poland, the UK and Spain — an estimated carbon footprint in kg of CO2 per year.

The advanced options let you split the price into net, VAT and excise duty, set up a two- or three-rate tariff (day/night, like the UK’s Economy 7 or Poland’s G12), add a standing charge, and adjust the billing period length — useful if you moved house mid-month. On top of the raw numbers, you also get something most electricity cost calculators skip entirely: a comparison of your usage and cost against other people who have run the same calculation, so a bare figure gets some context.

How to use the electricity cost calculator

Start by picking your country — it sets the currency, the quick price presets available, and whether you’ll see a CO2 footprint estimate.

Appliance mode:

  1. Pick an appliance from the list (fridge, washing machine, air conditioner, charger…) — the calculator fills in a typical wattage you can still edit, or enter the power yourself in watts or kilowatts.
  2. Enter how many hours a day it runs. Decimals are fine — 0.5 h is half an hour.
  3. Enter the price per kWh (in Poland or the UK you can pick a quick tariff preset instead).

Bill mode:

  1. Switch to “My bill / meter reading.”
  2. Enter your usage in kWh for a month or a year — the calculator converts to the other period automatically.
  3. Enter the price per kWh.

The result appears instantly: cost per day, month and year, usage in kWh, and a comparison against other users. In the advanced options you can add tax (if your price is net), a multi-zone tariff, a standing charge, or a custom billing period — each is explained below.

How electricity cost is calculated: the formula

The formula breaks down into three steps.

  1. Power to kilowatts. Watts are a small unit; kilowatt-hours are the one on your bill. Divide power by 1000.
  2. Energy in kWh. Multiply power in kW by the number of hours used and the number of days.
  3. Cost. Multiply the energy in kWh by the price per kWh.

Step-by-step example

Take an appliance rated at 1000 W — a typical wattage for an air conditioner — running 5 hours a day for 30 days, at a price of 0.30 per kWh (in whatever currency you use — the math is identical everywhere).

  1. Power in kW: 1000 ÷ 1000 = 1 kW.
  2. Daily energy: 1 kW × 5 h = 5 kWh/day.
  3. Monthly energy: 5 kWh × 30 days = 150 kWh.
  4. Monthly cost: 150 kWh × 0.30 = 45.00.

That’s exactly what the calculator does — only the numbers you enter change.

How much electricity common appliances use

This is the question people search for most, so here are some concrete numbers.

A fridge runs almost continuously — the compressor cycles on and off, but counting it as continuous 24-hour use at a typical 150 W, on Poland’s flat G11 tariff (an illustrative rate of 0.6189 PLN/kWh), it works out to 108 kWh and 66.84 PLN a month. In most homes, a fridge is the single biggest source of “always-on” usage, since it never switches off for good.

A washing machine draws a lot of power but only briefly. At 2000 W, run 3 times a week for 1 hour each time, that’s 25.71 kWh and 15.91 PLN a month at the same rate — so a single wash costs roughly 1.24 PLN (2 kWh × 0.6189 PLN).

A phone charger sits at the opposite end: 5 W for 2 hours a day is just 0.3 kWh a month — a few cents’ worth of electricity whatever your local rate. The calculator shows this figure at full precision instead of rounding it away to zero.

Want to check your own device? The wattage is usually printed on a label on the back or underside of the appliance, or in the manual, typically in watts.

Multi-zone tariffs: day/night rates around the world

A flat-rate tariff — Poland’s G11, for example — charges one price per kWh all day, every day. A multi-zone tariff splits the day into rate bands, usually a cheaper off-peak period and a pricier peak period, and needs a meter that can track both. The UK’s Economy 7 gives you roughly 7 cheaper night-time hours; Spain’s 2.0TD splits the day into three bands, often described loosely as off-peak/mid/peak.

Take a UK Economy 7 example: 2,500 kWh used over a year, with 40% of it in the cheaper night rate (an illustrative 0.14 GBP/kWh) and 60% in the pricier day rate (an illustrative 0.31 GBP/kWh), plus a standing charge of 0.5719 GBP/day. That works out to 208.33 kWh a month and 813.74 GBP for the year. Whether a multi-zone tariff is worth it depends entirely on how much of your usage you can actually shift into the cheap band — laundry, dishwashers and EV charging overnight are the classic candidates.

The calculator lets you set up to three zones and works out the cost of each one separately.

Taxes, standing charges and your carbon footprint

You can enter the price per kWh gross (what you actually pay) or net — in that case, fill in VAT and any excise duty in the advanced options and the calculator adds them for you. Example: a net price of 0.50 PLN/kWh plus 23% VAT gives an effective price of 0.615 PLN/kWh — a 1000 W appliance run 1 hour a day for 30 days (30 kWh) then costs 18.45 PLN, not the 15 PLN you’d get without the tax added on.

A standing charge (distribution, meter rental) applies regardless of how much you actually use — even with zero consumption, you still pay it in full. At a standing charge of 21.13 PLN a month with zero usage (an empty house for the whole billing period, say), the bill is still exactly 21.13 PLN.

For Poland, the UK and Spain, the calculator also adds an estimated carbon footprint, based on the average emissions factor of each country’s electricity grid (KOBiZE for Poland, DESNZ for the UK, MITECO for Spain) rather than any specific green-energy contract you might have. Example: 100 kWh a month in Poland is 1,200 kWh a year, which at Poland’s grid factor of 0.553 kg CO2/kWh comes to 663.6 kg of CO2 a year.

Frequently asked questions

How do I calculate the electricity cost of an appliance?

Divide the appliance’s power in watts by 1000 to get kilowatts, then multiply by the hours it runs per day and the number of days. For a 1000 W appliance running 5 hours a day over 30 days, that’s 1 kW × 5 h × 30 days = 150 kWh a month. Multiply that by your price per kWh to get the cost — at 0.30 per kWh, that’s 45 in your currency.

What is the average price per kWh?

There’s no single number — the price per kWh depends on your country, supplier, tariff, and whether you’re on a flat or multi-zone rate, and prices typically change at least once a year, sometimes more. Rather than searching for one figure online, enter the rate from your most recent bill directly into the calculator — that’s the only way to get a result that’s accurate for you.

How much electricity does a refrigerator use per day?

A fridge runs close to around the clock, so it’s counted as 24 hours a day. At a typical 150 W, that’s 3.6 kWh a day, or roughly 108 kWh a month. At an illustrative rate of 0.6189 PLN/kWh, that’s around 66.84 PLN a month — usually the single biggest source of constant, “always-on” usage in a home, since it never fully switches off.

How much does it cost to run a space heater per day or month?

Most space heaters draw around 1,500–2,500 W. Using the formula, a 2000 W heater run for 3 hours a day uses 2 kW × 3 h = 6 kWh a day, or about 180 kWh over 30 days — enter your own rate into the calculator above to see the exact cost. Because the relationship is linear, doubling the hours you run it doubles the cost of running that appliance.

How do I convert watts to kWh?

Watts measure power; kilowatt-hours measure energy used over time. Divide the power in watts by 1000 to get kilowatts, then multiply by the number of hours the device runs. A 500 W appliance running for 2 hours uses 0.5 kW × 2 h = 1 kWh. The calculator does this conversion automatically whether you enter power in watts or kilowatts.

How much does it cost to charge an EV, phone, or laptop?

It varies hugely by device. A phone charger draws around 5 W, so 2 hours of charging a day comes to just 0.3 kWh a month — pocket change whatever your rate. A laptop (typically around 65 W) uses more but is still a small monthly total. A home EV charger, by contrast, is usually rated around 7.4 kW — over a thousand times the power of a phone charger — so charging an EV is the one case in this list worth entering into the calculator directly rather than estimating by eye.

What uses the most electricity in a house?

Usually heating and heating-adjacent appliances: electric space heaters, water heaters, tumble dryers, ovens and induction hobs, which typically draw 2,000–3,000 W and often run for extended periods. A fridge draws far less power but runs 24 hours a day, so it still adds up to a meaningful monthly total. Small electronics — routers, chargers, a TV on standby — draw very little power each, so they contribute relatively little to the bill even though they’re never switched off.

How much is the average electricity bill per month?

It depends heavily on household size, climate and heating type, so there’s no single “average” that applies everywhere. As one reference point: a UK household on an Economy 7 tariff using 2,500 kWh a year, with 40% of that on the cheaper night rate, comes to about 813.74 GBP for the year — roughly 68 GBP a month. Enter your own usage into the calculator’s bill mode to see how you compare against other users, not just a national average.

How much does it cost to run an air conditioner per hour?

A typical air conditioner draws around 1,000 W. Run for 5 hours a day over a 30-day month, that’s 150 kWh, which at 0.30 per kWh comes to 45 in your currency for the month — or roughly 1.50 a day. Cost scales directly with hours of use, so cutting run time in half halves the cost of running that unit.

How do I read my electricity bill and calculate real usage?

Read the meter at the start and end of a billing period (say, a month) and subtract the two figures — the difference is your usage in kWh. You can also just copy the usage figure straight off your latest bill. In the calculator, switch to “My bill / meter reading,” enter that number and your price per kWh — daily, monthly and yearly cost are worked out automatically from there.

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