Energy Bill Estimator
Build your monthly bill from usage, rate, fixed charges, and tax — and the true all-in $/kWh.
Updated
The per-kWh supply rate from your bill.
The service/connection fee on your bill.
Advanced
Utility/sales tax applied to the bill, if any.
You need
$181.13/month
900 kWh all-in
- Energy charge
- $157.50
- + Fixed charge
- $15.00
- True all-in rate
- $0.2013/kWh
In short
How do I estimate my electric bill?
Multiply your monthly kilowatt-hours by your supply rate, add the fixed monthly charge, then apply tax to the subtotal. At 900 kWh, $0.175 per kWh, a $15 fixed charge and 5 percent tax, the bill is $181.13 and the true all-in cost is $0.2013 per kWh, about 15 percent above the headline rate.
This is an estimate built from the numbers you enter, not a prediction of what your utility will invoice, and it is not financial advice.
How to use the energy bill estimator
Enter your monthly usage in kilowatt-hours and your supply rate, add the fixed monthly charge printed on your bill, put any tax percentage under Advanced, and the tool returns the total bill plus the genuinely useful output: your true all-in cost per kilowatt-hour once everything is counted. All four inputs should come off a statement rather than from memory.
The Energy Information Administration put the US residential average at 18.44 cents per kilowatt-hour in May 2026 in its Electric Power Monthly released 23 July 2026, but that same table showed Idaho at 12.35 cents and Hawaii at 52.00 cents in the same month, so an average tells you what the country pays and nothing at all about what you pay.
$181.13
Estimated bill
900 kWh at $0.175, $15 fixed, 5% tax
$0.2013
True all-in rate
total divided by the kilowatt-hours
+15%
Above the headline
what the quoted rate leaves out
The reason to care about the all-in rate is that the per-kilowatt-hour price a utility or a retail plan advertises is only the energy component. Your real cost per unit is the whole bill divided by the kilowatt-hours you used, and it is always higher, because fixed charges and tax do not disappear just because they are not quoted per unit.
That all-in number is the honest basis for comparing one plan against another, for judging a fixed-rate offer against a variable one, and for deciding whether an efficiency upgrade will save what a salesperson claims. Use the headline rate for arithmetic and the all-in rate for decisions.
Now spend that all-in rate somewhere
The all-in figure is the rate worth carrying into any tool that asks what electricity costs you, starting with what a single device costs to run.
Open the electricity cost calculator →Do
- Take the usage, the rate and the fixed charge straight off a recent statement.
- Add any per-kilowatt-hour delivery charge to the supply rate, since both scale with usage.
- Enter a blended average for a tiered or time-of-use plan.
- Compare two plans on the all-in rate rather than the advertised one.
Don't
- Leave the tax field at zero when your statement taxes the whole subtotal.
- Expect cutting consumption to drive the bill toward zero, because the fixed charge stays.
- Try to model a residential demand charge here, which no flat rate can represent.
- Treat the total as an invoice; it is arithmetic on the four numbers you typed.
How the fixed charge quietly rewrites your rate. Every row uses the tool defaults of $0.175 per kWh, a $15 fixed monthly charge, and 5 percent tax, and varies only the monthly usage. The all-in column is the total bill divided by the kilowatt-hours, which is the number that actually describes what you pay per unit.
| Monthly usage, kWh | Energy charge at $0.175/kWh | Total bill with $15 fixed and 5 percent tax | True all-in rate, $/kWh | Premium over the 17.5 cent headline |
|---|---|---|---|---|
| 100 | $17.50 | $34.13 | $0.3413 | plus 95 percent |
| 150 | $26.25 | $43.31 | $0.2888 | plus 65 percent |
| 200 | $35.00 | $52.50 | $0.2625 | plus 50 percent |
| 300 | $52.50 | $70.88 | $0.2363 | plus 35 percent |
| 400 | $70.00 | $89.25 | $0.2231 | plus 27.5 percent |
| 500 | $87.50 | $107.63 | $0.2153 | plus 23 percent |
| 600 | $105.00 | $126.00 | $0.2100 | plus 20 percent |
| 750 | $131.25 | $153.56 | $0.2048 | plus 17 percent |
| 900 (the tool default) | $157.50 | $181.13 | $0.2013 | plus 15 percent |
| 1,000 | $175.00 | $199.50 | $0.1995 | plus 14 percent |
| 1,200 | $210.00 | $236.25 | $0.1969 | plus 12.5 percent |
| 1,500 | $262.50 | $291.38 | $0.1943 | plus 11 percent |
| 2,000 | $350.00 | $383.25 | $0.1916 | plus 9.5 percent |
| 3,000 | $525.00 | $567.00 | $0.1890 | plus 8 percent |
Why a fixed charge quietly rewrites your rate
Fixed charges are the part almost everyone forgets. Most bills carry a fixed monthly service, connection, or customer charge, commonly in the ten to twenty dollar range in the US, that you owe no matter how little electricity you use. It pushes your effective rate up hardest at low usage, and it is precisely why cutting consumption never drives a bill toward zero.
The same structure exists elsewhere under different names: in Great Britain the Ofgem default tariff cap explicitly sets a maximum unit rate and a separate daily standing charge, and for the period 1 July to 30 September 2026 Ofgem set the cap at the equivalent of 1,663 pounds a year for a typical direct-debit household. Pull the exact figure off your own bill.
The formula, worked line by line
The bill is the energy you used priced at your rate, plus the fixed charge you owe regardless of usage, with tax applied to the whole subtotal. The all-in rate is then the total divided by your usage, which is the single most useful number this page can hand you.
That last division is worth doing deliberately rather than treating as a by-product. It converts a bill full of separately named line items into one comparable price per kilowatt-hour, and because the fixed charge is spread across whatever usage you happened to have, the answer moves with consumption even when no rate has changed.
energy charge = kWh x rate
subtotal = energy charge + fixed charge
total = subtotal x (1 + tax percent / 100)
all-in rate = total / kWh- Energy charge
- 900 × $0.175 = $157.50
- Fixed charge
- + $15.00
- Subtotal
- $172.50
- Tax
- × 1.05
- Total bill
- $181.13
Divide that by 900 kWh and the true all-in rate is $0.2013 per kWh, about 15 percent above the $0.175 headline you started from.
Read it: A light user is effectively paying nearly double the advertised price per unit, which is the arithmetic behind the complaint that using less never seems to save proportionally.
The gap widens because the same fixed charge is spread over fewer kilowatt-hours; every row uses the identical $0.175 rate, $15 fixed charge, and 5 percent tax. At 300 kWh the inputs give a $70.88 bill, and at 100 kWh, $34.13.
Questions people ask
How do I estimate my electric bill?
Multiply your monthly kilowatt-hours by your supply rate, add the fixed monthly charge, then apply any tax to the subtotal. With the tool defaults of 900 kWh at $0.175 per kWh, a $15 fixed charge, and 5 percent tax, that is $157.50 plus $15, times 1.05, giving $181.13. Take the usage and the fixed charge straight off a recent statement rather than estimating them, and use a rate that includes any per-kilowatt-hour delivery charges, not just the supply component.
What is the true cost per kWh?
It is the whole bill divided by the kilowatt-hours you used. On the tool defaults that is $181.13 divided by 900, which is $0.2013 per kWh against a $0.175 headline rate, about 15 percent higher once the fixed charge and tax are counted. That all-in figure is the honest number to compare against another plan, another month, or another home, because it already contains everything the advertised rate leaves out. It is also the rate worth entering into any other calculator that asks what electricity costs you.
What is the fixed or service charge on my bill?
It is a flat monthly fee, often called a service, connection, customer, or standing charge, that you owe regardless of how much electricity you use, and it commonly falls in the ten to twenty dollar range in the US. It covers the utility cost of keeping you connected, metered, and billed. It is the reason a bill never reaches zero even in a month you were away, and the reason your effective per-kilowatt-hour cost climbs sharply at low usage, since the same fee is divided across fewer units.
Why is my effective rate higher than the advertised rate?
Because the advertised rate is only the energy charge. Your bill also carries the fixed monthly charge, taxes on the subtotal, and in deregulated US markets and in Great Britain a delivery or distribution charge shown separately from supply. Every one of those raises the real cost of each kilowatt-hour without appearing in the quoted price. The effect is strongest at low usage: with a $15 fixed charge and 5 percent tax, a 100 kWh month works out at $0.3413 per kWh against a $0.175 headline, while a 3,000 kWh month lands at $0.1890.
Does this handle tiered or time-of-use rates?
It uses a single flat rate, which is exactly right for standard plans and a fair approximation for others. If you are on a tiered plan, where the price steps up past a usage threshold, or a time-of-use plan, where peak hours cost more than off-peak, enter your blended average instead: take the total energy charge from a recent bill and divide it by the total kilowatt-hours it covered. Residential demand charges, which bill your highest short-interval draw of the month, cannot be modelled by any flat rate and need your utility tariff sheet.
Sources
Where the constants and formulas on this page come from. Each line names the figure it backs.
The 18.44 cents per kWh US residential average for May 2026 and the 12.35 cent Idaho and 52.00 cent Hawaii figures for the same month.
Electric Power Monthly, Table 5.6.A — Average price of electricity by state — US Energy Information Administration, May 2026
The default tariff cap of 1,663 pounds a year for a typical direct-debit household from 1 July 2026, up from 1,641 pounds.
Energy price cap will rise from July — Ofgem, Cap period 1 July to 30 September 2026; resets quarterly
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