By Tim King · Updated 7 October 2026

Electricity Cost Calculator

Price per kWh to Cost a Month

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Electricity used (kWh)

Over a

Usage tariff (cents per kWh)

Daily supply charge (cents per day, optional)

Result

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How the Electricity Cost Calculator works

This electricity cost calculator turns kWh and your price per kWh into money: usage times the unit price, plus any daily supply charge. 1,500 kWh at 30 cents per kWh is 450. Enter the kilowatt-hours from your meter or bill, the period they cover and your tariff, add the daily supply charge if you pay one (every Australian bill has one), and the page shows the cost for the period and the same use costed per day, month and year, with a table of what it would cost at other kWh prices.

Electricity cost calculator: usage, supply and the year ahead

Most people look at the total on an electricity bill and nothing else. That makes it hard to tell whether a new plan is cheaper, whether a heat pump paid off, or why the winter bill doubled. This page splits the bill into the two charges that make it up and scales the result to a day, a month and a year. So a quarterly bill and a monthly one compare like for like.

The formula

Usage charge = kWh used × tariff in cents ÷ 100.

Supply charge = daily supply charge in cents ÷ 100 × days in the period.

Cost for the period = usage charge + supply charge.

The calculator uses calendar-average period lengths: a week is 7 days, a month is 30.44, a quarter is 91.31 and a year is 365.25. A real bill covers the exact days between meter reads, often 88 to 94 for a quarter, so expect the supply line to differ by a few cents a day's worth. Per day, per month and per year all come from the same daily figure, so they always agree with each other.

Worked examples

The first example is the default: 1,500 kWh over a quarter at 30 cents with a 110-cent daily supply charge. The usage charge is 1,500 × 30 ÷ 100 = $450.00. The supply charge is 1.10 × 91.31 = $100.44. The quarter costs $550.44, which is $6.03 a day, $183.48 a month and $2,201.78 a year. Average use shows 16.4 kWh a day.

The second example compares two plans on that same usage. Plan A charges 30 cents and 110 cents a day. Plan B charges 28 cents but 140 cents a day. Plan B's quarter comes to $547.84, just $2.60 cheaper. The 2-cent saving on usage and the 30-cent extra on supply cancel out at 15 kWh a day (30 ÷ 2). A household using more than 15 kWh a day saves with Plan B; one using less saves with Plan A.

How many dollars a year is my daily use?

Divide the kWh on your bill by the days it covers to get daily use, then read across. The table uses a 110-cent supply charge, which adds about $402 a year to every row. Yearly electricity cost by daily use and tariff, with a 110 c/day supply charge

kWh a day	25 c/kWh	30 c/kWh	35 c/kWh	40 c/kWh
3	$676	$731	$785	$840
4	$767	$840	$913	$986
5	$858	$950	$1,041	$1,132
6	$950	$1,059	$1,169	$1,278
8	$1,132	$1,278	$1,424	$1,571
10	$1,315	$1,498	$1,680	$1,863
12	$1,498	$1,717	$1,936	$2,155
14	$1,680	$1,936	$2,192	$2,447
15	$1,771	$2,045	$2,319	$2,593
16	$1,863	$2,155	$2,447	$2,739
18	$2,045	$2,374	$2,703	$3,032
20	$2,228	$2,593	$2,959	$3,324
22	$2,411	$2,812	$3,214	$3,616
24	$2,593	$3,032	$3,470	$3,908
25	$2,685	$3,141	$3,598	$4,054
26	$2,776	$3,251	$3,726	$4,200
28	$2,959	$3,470	$3,981	$4,493
30	$3,141	$3,689	$4,237	$4,785
35	$3,598	$4,237	$4,876	$5,515
40	$4,054	$4,785	$5,515	$6,246
50	$4,967	$5,881	$6,794	$7,707

How to read the result

Cost for the period is the bill you should expect for the period you chose, before discounts, concessions, solar credits or any tax your retailer adds on top.
Usage charge is the part you control by using less.
Supply charge is fixed. On a low-use home it can be a third or more of the bill; in the first example it is 18%.
Per day, per month and per year rescale the same daily cost. Per year from one winter quarter will overstate the annual bill, because heating use is seasonal.
Average use per day is the figure to compare with other homes and with the table above.

The table under the result reprices your usage at tariffs from 20 to 50 cents.

Where the numbers come from

Energy is billed in kilowatt-hours: one kWh is a 1,000-watt load running for an hour. In Australia, the Default Market Offer and the Victorian Default Offer set a reference price that retailers must quote their plans against. In the UK the Ofgem price cap sets a unit rate and a standing charge in pence per day, which works with this page exactly as a supply charge does. Many US utilities bill a fixed monthly customer charge instead; divide it by 30.44 to get a daily figure.

Tips and pitfalls

Time-of-use plans. Peak, shoulder and off-peak kWh are listed separately on the bill. Run the page once per block with the supply charge only on one run, then add the results.
Controlled load. Off-peak hot water on its own meter is a second calculation.
Solar. The meter's import kWh is what you pay for. Feed-in credits come off the total afterwards and do not change the tariff.
Blank supply charge. Leaving it empty costs usage only.

To cost one appliance from its wattage, use the appliance running cost calculator. To turn a joule or megajoule figure into kWh first, use joules to kWh.

Sources: Kilowatt-hour.

Checked against: 1,500 kWh at 0.25 per kWh = 375

FAQ

How do I calculate my electricity cost?

Multiply the kilowatt-hours used by the tariff in cents and divide by 100 for the usage charge, then add the daily supply charge times the number of days. 1,500 kWh at 30 cents is $450; 91 days at 110 cents is $100.10; the bill is about $550 before any discounts or credits.

How do I find my electricity price per kWh?

Your bill states it as the usage rate or unit rate. If it does not, divide the usage charge by the kWh used: 450 for 1,500 kWh is 30 cents per kWh. Leave out the supply or standing charge, which is billed per day rather than per unit.

What is a kilowatt-hour?

It is the energy used by a 1,000-watt appliance running for one hour, or a 100-watt one for ten hours. Electricity is metered and billed in kWh. A household uses somewhere between 5 and 30 kWh a day depending on its size, climate and whether hot water and cooking are electric.

What is a supply charge and can I avoid it?

It is a fixed daily fee for the connection to the network and applies regardless of use. It cannot be avoided while connected, but it varies between plans, so a household with low usage should favour a plan with a low daily charge even if the usage rate is slightly higher.

What is the average electricity tariff in Australia?

In 2025 most residential single-rate tariffs fall between about 25 and 45 cents per kWh depending on the state and retailer, with supply charges of roughly 90 to 130 cents a day. The default of 30 cents here is a round mid-range figure; replace it with the rate on your own bill.

Does the calculator work for other countries?

Yes. The maths is the same everywhere: units used times the rate, plus any fixed daily or monthly charge. Enter the tariff in pence, cents or the hundredth of your currency and the results read in the whole unit. Leave the supply charge blank if your bill has a monthly fixed charge instead, and add it separately.