# What does it cost to run per kWh?

Computes the electricity an appliance uses in kilowatt-hours from its power and hours of use a day, and what that costs per day, month and year at a price per kWh.

- Page: https://www.acalculator.org/everyday-life/electricity-cost-calculator
- JSON spec: https://www.acalculator.org/everyday-life/electricity-cost-calculator.json
- Version: cca537efb134

## Default answer

Example with the default inputs (Power 1,500 W, Hours a day 3, How many 1, Price (¢/kWh) 18.31): Using 4.5 kWh a day costs $25.06 a month.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| power | Power | The power the appliance draws while on, from its label or a plug-in meter. |
| hours | Hours a day | How many hours a day the appliance is on. |
| qty | How many | How many of these appliances. |
| rate | Price (¢/kWh) | The price of electricity in cents per kilowatt-hour, from your bill. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| perMonth | Cost per month | The cost for an average month of 365 ÷ 12 days. |
| perDay | Cost per day | kWh a day × the price. |
| perYear | Cost per year | The cost for 365 days. |
| energyDay | Energy per day | Power × hours a day × how many. |
| energyYear | Energy per year | The energy per day × 365. |

## Method

kWh a day = power (kW) × hours a day × how many; cost a day = kWh × price; a month = 365 ÷ 12 days; a year = 365 days

## Assumptions

- The power is the average the appliance draws while on. Appliances that cycle, such as refrigerators, draw less on average than their label.
- The price is a flat rate per kWh. Bills with tiers, time-of-use rates, fixed charges or taxes cost more or less.
- The default price is the US average residential price for July 2026, 18.31¢ per kWh, from the EIA.

## Worked examples

1. power = 1,500, hours = 3, qty = 1, rate = 18.31 gives energyDay = 16,200,000, perDay = $0.82, perMonth = $25.06, perYear = $300.74. Source: hand calculation in content.mdx: 1.5 kW × 3 h = 4.5 kWh × $0.1831 = $0.824 a day; × 30.42 = $25.06 a month; × 365 = $300.74 a year.
2. power = 10, hours = 5, qty = 8, rate = 15 gives energyDay = 1,440,000, perYear = $21.90. Source: hand calculation in content.mdx: 8 × 10 W × 5 h = 400 Wh = 0.4 kWh; × 365 = 146 kWh × $0.15 = $21.90 a year.
3. power = 200, hours = 24, qty = 1, rate = 20 gives energyYear = 6,307,200,000, perYear = $350.40. Source: hand calculation in content.mdx: 0.2 kW × 24 h = 4.8 kWh a day; × 365 = 1,752 kWh × $0.20 = $350.40.

## FAQ

### How do I calculate the cost of running an appliance?

Multiply the power in kilowatts by the hours of use to get kilowatt-hours (kWh), then multiply by your price per kWh. A 1,500 W heater used 3 hours a day uses 1.5 × 3 = 4.5 kWh; at 18.31¢ per kWh that is $0.82 a day, or about $25 a month.

### How do I convert watts to kWh?

kWh = watts × hours ÷ 1,000. A 100 W bulb on for 10 hours uses 100 × 10 ÷ 1,000 = 1 kWh.

### What is the average price of electricity?

The U.S. Energy Information Administration reports a US average residential price of 18.31¢ per kWh for July 2026, the default here. Prices differ a lot by state and by utility, so use the price on your own bill: divide the energy charge by the kWh used.

### Where do I find an appliance’s wattage?

On the label or nameplate, often on the back or bottom, or in the manual. If the label only gives amps, multiply by the voltage (120 V in most US homes) for an estimate of the watts. A plug-in energy meter measures the real use.

### Why is my refrigerator’s cost lower than the label suggests?

A refrigerator’s compressor cycles on and off, so over a day it draws less than its rated power. Enter its average power, or use the yearly kWh on its EnergyGuide label with 24 hours a day.

### Why does my bill not match?

Bills add fixed monthly charges, taxes and delivery fees, and many utilities use tiered or time-of-use prices. The calculator uses one flat price per kWh.

## Sources

- U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A: US total residential price 18.31¢ per kWh, July 2026 (released September 24, 2026). https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_a
- NIST SP 811 (2008), Appendix B: 1 kWh = 3.6 MJ; 1 W = 1 J/s.