Electricity Bill Calculator
Estimate your monthly electricity bill from average daily usage, the number of days, your per-kWh rate, and any fixed service charge.
How to use this tool
- Find your average daily usage (recent bill kWh divided by its days).
- Enter the number of days the billing period covers.
- Enter your all-in energy rate in dollars per kWh.
- Add any flat monthly service charge from your bill.
- Read the total usage, energy charge, and estimated bill.
Estimate your power bill before it arrives. Enter your daily usage, the length of the billing period, your rate, and any fixed charge to see the energy cost and total bill.
Formula
The bill is the metered energy charge plus a flat service fee:
Usage (kWh) = Daily usage × Days
Energy charge = Usage × Rate
Estimated bill = Energy charge + Fixed charge
How it works
A residential electricity bill has two main parts: a volumetric energy charge that scales with how much you use, and one or more fixed charges that you pay just for being connected. This calculator models the common flat-rate structure: it multiplies your average daily kilowatt-hours by the days in the period to get total usage, prices that usage at your per-kWh rate, and adds the fixed service fee.
Average daily usage is the easiest input to estimate: divide a recent bill's total kWh by its number of days, or read your daily figures from a utility app. The rate should be your all-in energy price including delivery and supply per kWh, since many bills split those into separate line items.
The model assumes a single flat rate. It does not handle tiered (block) pricing, time-of-use periods, demand charges, or seasonal rates, all of which can change the marginal price of additional usage. For a tiered or TOU plan, run the calculator separately for each block or period and sum the results.
Worked example
30 kWh/day for 30 days at $0.15/kWh, $10 fixed
- Usage = 30 kWh × 30 days = 900 kWh.
- Energy charge = 900 kWh × $0.15 = $135.00.
- Estimated bill = $135.00 + $10.00 fixed = $145.00.
Total usage 900.00 kWh | Energy charge $135.00 | Estimated bill $145.00
Monthly energy charge by daily usage and rate (30 days, no fixed fee)
| Daily usage | At $0.10/kWh | At $0.15/kWh | At $0.20/kWh |
|---|---|---|---|
| 10 kWh/day | $30.00 | $45.00 | $60.00 |
| 20 kWh/day | $60.00 | $90.00 | $120.00 |
| 30 kWh/day | $90.00 | $135.00 | $180.00 |
| 40 kWh/day | $120.00 | $180.00 | $240.00 |
Key terms
- Kilowatt-hour (kWh)
- The standard unit of electrical energy: one kilowatt of power drawn for one hour. Utilities bill energy in kWh.
- Energy charge
- The variable part of the bill that equals usage times the per-kWh rate. It rises and falls with consumption.
- Fixed (service) charge
- A flat monthly fee for being connected to the grid, independent of how much energy you use.
- Time-of-use (TOU) rate
- A pricing plan where the per-kWh rate changes by time of day, typically higher during peak demand hours.
Frequently asked questions
- How do I find my average daily kWh usage?
- Take the total kilowatt-hours from a recent bill and divide by the number of days that bill covers. A typical US home uses roughly 25–35 kWh per day, but it varies widely with home size, climate, and appliances.
- Why doesn't my estimate match my bill exactly?
- Real bills can include tiered pricing, time-of-use rates, taxes, riders, and delivery fees beyond a single flat rate and one fixed charge. Use your all-in per-kWh price and add other fixed line items to the fixed-charge field for a closer match.
- What's the difference between supply and delivery charges?
- Supply is the cost of generating the electricity; delivery is the cost of transmitting it to your home. Both are usually charged per kWh, so add them together for the rate input.