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kWh in, dollars out, fixed charge and tax included. Enter the kWh your meter shows, the rate per kWh from your tariff, the fixed monthly charge and any tax, and this page prints the usage charge, the fixed charge, the tax and the total — plus the all-in cost per kWh. It is the same arithmetic whether you call it an energy bill calculator or a power bill calculator.
Your electricity bill for 1,000 kWh
$0.1500 per kWh × 1,000 kWh + $12.50 fixed charge
The fixed charge is the customer or service charge that arrives whatever you use. Tax and fees are a percentage of the bill before tax — leave it at 0 if your bill prints them as a dollar amount and you have added that amount to the fixed charge instead.
The usage charge is rounded once, to the cent, after the kWh are multiplied by the rate. Tax is then applied to the bill before tax. Every row above can be checked by hand.
Four monthly usages on the same tariff — a $0.1500 rate and a $12.50 fixed charge. The bar is what each kWh actually costs once the fixed charge is spread over the usage.
A bill is not the kWh multiplied by the rate, and the difference is usually the part people are surprised by. The usage charge is the kWh times the rate; the fixed charge is a flat amount that arrives whatever the meter says; tax and fees are charged on top of both. The calculator above keeps all three separate so the total can be rebuilt line by line.
The kWh is in the meter-reading block: the present reading minus the previous reading, sometimes multiplied by a meter multiplier printed beside it. The rate is on the usage or supply line, usually quoted in cents per kWh — divide it by 100 for this field, so 15.00 cents is 0.1500. The fixed charge goes by several names: customer charge, service charge, basic service fee, standing charge. Tax and fees are the taxes, riders and surcharges lines; if your bill prints them as a dollar amount rather than a percentage, add that amount to the fixed charge and leave the tax field at 0, because the arithmetic is the same.
The same tariff produces a different all-in cost per kWh at every level of usage, because the fixed charge does not scale with the meter. On a $0.1500 rate with a $12.50 fixed charge:
| Monthly usage | Usage charge | Fixed charge | Bill | All-in per kWh |
|---|---|---|---|---|
| 250 kWh | $37.50 | $12.50 | $50.00 | $0.2000$0.0500 above the rate |
| 500 kWh | $75.00 | $12.50 | $87.50 | $0.1750$0.0250 above the rate |
| 1,000 kWh | $150.00 | $12.50 | $162.50 | $0.1625$0.0125 above the rate |
| 2,000 kWh | $300.00 | $12.50 | $312.50 | $0.1563$0.0063 above the rate |
At 1,000 kWh the fixed charge is 7.69% of the bill. At 250 kWh it is a quarter of it. That is the whole reason a small flat on the same tariff can be paying the equivalent of $0.2000 a kWh while a large one pays $0.1563 — and why comparing two households by the rate on the bill, rather than by the all-in figure, gets the answer wrong.
Many tariffs split the kWh into blocks rather than charging one rate for everything: the first block at one price, the rest at another. Take 1,200 kWh with the first 800 at $0.1200 and the remaining 400 at $0.1900. The first block is $96.00, the second is $76.00, so the usage charge is $172.00, and a $9.00 fixed charge makes the bill $181.00 — an all-in $0.1508 per kWh.
Run that same 1,200 kWh through a single flat rate and you would need $0.1433 to land on the same usage charge — but that rate is only right at exactly 1,200 kWh. At 900 kWh the blocks would give a different average, and at 1,500 kWh a different one again. So on a tiered bill, either run each block through this page separately and add the usage charges, or put the average rate of the blocks you actually used in the rate field and read the usage charge as the check rather than the input.
A kWh is 1,000 watt-hours, which is a 1,000-watt appliance running for one hour. A 1,500-watt space heater on for an hour is 1.5 kWh; the same heater on for six hours is 9 kWh. At $0.1500 a kWh that is $1.35, and 100 kWh less over a month takes $15.00 off the usage line — the fixed charge does not move, which is why cutting usage by 10% cuts the bill by less than 10%.
It does not know your tariff, your tier boundaries, your meter multiplier or your time-of-use windows. It multiplies what you give it, and it prints every step so the arithmetic can be checked. A demand charge is the one line to be careful with: it is priced in kW rather than kWh, it is not a fixed charge, and folding it into the fixed field will give a bill that is right for one month and wrong for the next.
Multiply the kWh used by the rate per kWh to get the usage charge, add the fixed monthly charge, then add tax and fees if your bill charges them. At 1,000 kWh on a $0.1500 rate with a $12.50 fixed charge: 1,000 × 0.1500 is $150.00, plus $12.50 is $162.50, and with 8% tax on top that is $13.00 more, $175.50. The order matters: tax is charged on the bill before tax, not on the usage charge alone.
Yes — both names describe the same question, which is what a quantity of electricity costs once the rate, the fixed charge and the tax are applied. Energy is the kWh, power is the kW, and a residential bill is charged on energy, so a power bill calculator and an energy bill calculator run the same arithmetic. This page is that arithmetic with each line shown.
Because the fixed charge and the taxes are not in the rate. On a $162.50 bill built from $150.00 of usage, the fixed charge is $12.50 — 7.69% of the total — and it would be there at zero usage. Taxes, riders and surcharges are then charged on the sum of both. If the gap is larger than those two lines explain, the rate on the bill is probably an average of tiered blocks, which is the case covered above.
It depends entirely on the rate and the fixed charge, and both are printed on the bill. At $0.1500 a kWh with a $12.50 fixed charge it is $162.50; at $0.1600 it is $172.50. This page will not guess a national average for you — type the two numbers from your own tariff and the answer is exact to the cent.
The rate on the bill often does not change at all; the fixed charge is simply spread over a different number of kWh. The same $12.50 over 250 kWh adds $0.0500 to every kWh, over 1,000 kWh it adds $0.0125, and over 2,000 kWh $0.0063. A high-usage summer month and a low-usage spring month on an unchanged tariff will still show two different all-in rates.
No. Gas is billed in therms or cubic metres and water in gallons or cubic metres, and neither converts to kWh without a calorific value or a different tariff structure. This page is electricity only, kWh only. The method — usage × rate, plus a fixed charge, plus tax — is the same shape, but the units in the fields would be wrong.
Then the kWh in the field is an estimate, and the arithmetic is exact but the input is not a measurement. An estimated bill is trued up against the next actual reading, so a month that looks high is often followed by one that looks low. Enter the kWh printed on the bill you are checking, not the kWh you think you used.