Electricity Bill Calculator
Calculate electricity use and estimate the final bill from a flat price per kWh, fixed charges, adjustments or credits, and tax.
Estimate your electricity bill
Start with meter readings or enter total kWh directly.
How to Calculate an Electricity Bill
First calculate electricity usage. When a digital or analog meter reports cumulative kilowatt-hours, subtract the previous reading from the current reading. A previous reading of 8,240 and a current reading of 8,565 gives 325 kWh used. In ordinary electricity billing, one “unit” usually means one kilowatt-hour.
Next multiply usage by the entered rate: energy charge = kWh × price per kWh. Add fixed charges and any positive adjustments, subtract credits, and apply tax or VAT to the subtotal if the tariff requires it. The calculator keeps each step visible so you can compare it with a bill rather than seeing only an unexplained total.
Electricity Bill Formula
Usage = current meter reading − previous meter reading
Energy charge = usage in kWh × rate per kWh
Pre-tax subtotal = energy charge + fixed charges + adjustments
Estimated bill = pre-tax subtotal + tax
If the entered adjustment is a credit, use a negative number. The calculator will not accept a credit large enough to make the pre-tax subtotal negative because that usually indicates that the bill’s credit rules need separate treatment.
Worked Electricity Bill Example
Suppose a home used 325 kWh in 30 days. At USD 0.18 per kWh, the energy charge is USD 58.50. Add USD 12.00 of fixed charges to get USD 70.50 before tax. A 5% tax is USD 3.525, which rounds to USD 3.53, producing an estimated total of USD 74.03.
The result also shows average daily use and a 30-day kWh projection. Those figures describe consumption, not a guaranteed future bill. Seasonal heating or cooling, occupancy, operating hours and tariff changes can make another billing period different.
Why Your Utility Bill May Differ
Many tariffs are not a single flat price. A provider may charge different rates for usage blocks, peak and off-peak hours, seasonal periods or total demand. Bills may also contain fuel-cost adjustments, renewable-energy charges, meter fees, subsidies, minimum charges, late fees and taxes applied to different parts of the subtotal.
Use the flat-rate calculator when your rate is truly flat or when the bill provides an effective average price per kWh. If your tariff is tiered, calculate each block separately from the provider’s current schedule. If the meter has rolled over, use the total-kWh input rather than entering a current reading smaller than the previous reading.
Meter Readings Versus Appliance Estimates
Meter readings measure the combined energy recorded for the property. An appliance estimate starts with watts and operating time: watts × hours ÷ 1,000 = kWh. Appliance calculations are useful for planning, but actual consumption can differ because many devices cycle on and off, change power level or draw standby power.
For a whole bill, use verified meter or utility-portal kWh when available. To estimate a single appliance before the bill arrives, use the Electricity Consumption Calculator, then bring its kWh result into this page.
Source and Unit Reference
The U.S. Department of Energy explains that electricity use over time is measured in kilowatt-hours. See Electricity 101. The rate, tax and other charge rules in this calculator are supplied by the user because utility tariffs vary by location and provider.
Frequently Asked Questions
How do I calculate a bill from meter readings?
Subtract the previous reading from the current reading, multiply the difference by the rate per kWh, add fixed charges and adjustments, then apply tax if required.
What is one electricity unit?
For ordinary utility billing, one unit is one kilowatt-hour (1 kWh).
Does this support slab or tiered rates?
No. It uses one flat rate per kWh. Calculate tariff blocks separately or use the current calculator supplied by your utility.
Can I enter a credit?
Yes. Enter the credit as a negative adjustment, such as −10.00.