Electricity cost formula
kWh = watts × hours ÷ 1000. Cost = kWh × your rate per kWh. Example: a 1,500-watt space heater running 5 hours a day, at the US average rate (18.31¢/kWh):
- Energy per day: 1,500 × 5 ÷ 1000 = 7.5 kWh
- Cost per day: 7.5 × $0.1831 = $1.37
- Cost per month (30 days): $41.20
- Cost per year: $501
How much does it cost to run a space heater?
A typical 1,500W space heater run 5 hours a day costs about $41.20 a month at the US average rate. Running it longer, or a higher-wattage heater, scales up directly -- use the calculator above with your own hours and heater wattage (check its label; most run 750-1,500W).
How much electricity does a TV use?
A typical LED TV (~100W) run 5 hours a day uses about 15 kWh a month, costing around $2.75 at the US average rate -- one of the cheaper devices to run compared to heating/cooling appliances. Larger or older TVs can use several times as much power.
Default rate: US average residential electricity price
The calculator's default rate is the US average residential price of electricity, 18.31¢/kWh, from the U.S. Energy Information Administration's Electric Power Monthly (Table 5.6.A), July 2026 data (EIA's report lags about two months, so this is the most recent figure available). It's a national average -- EIA's own state-by-state data shows residential rates from roughly 13 to 53 cents/kWh depending on the state and utility, so replace the default with the rate from your own bill for an accurate estimate.
Typical appliance costs (at the US average rate)
| Appliance | Typical watts | Hours/day (assumed) | Cost/month | Cost/year |
|---|---|---|---|---|
| LED light bulb | 10 W | 6 h | $0.33 | $4 |
| Laptop | 50 W | 6 h | $1.65 | $20 |
| Refrigerator | 150 W | 24 h | $19.77 | $241 |
| TV (LED, ~50") | 100 W | 5 h | $2.75 | $33 |
| Window air conditioner | 1000 W | 8 h | $43.94 | $535 |
| Space heater | 1500 W | 5 h | $41.20 | $501 |
| Electric water heater | 4000 W | 3 h | $65.92 | $802 |
| EV charger (Level 2) | 7000 W | 2 h | $76.90 | $936 |
Wattages are typical/illustrative -- check your own appliance's label for its actual rating, and use the calculator above with your own hours of use.
Tips to lower your electricity bill
- Heating and cooling are usually the biggest loads in a home -- a programmable thermostat and better insulation often save more than switching off small devices.
- Water heating (especially electric) is a large, steady load; a lower thermostat setting and shorter showers reduce it directly.
- Phantom loads (devices left on standby) add up in aggregate but are individually small compared with heating, cooling and water heating.
- Check your utility's rate plan -- some offer time-of-use rates where running large appliances at off-peak hours costs less per kWh.
More electrical & energy tools
- Watts to amps calculator: find the current an appliance draws from its wattage.
- Amps to watts calculator: find the wattage from a nameplate amp rating.
- BTU calculator: size an air conditioner or heater, then estimate its running cost here.
Frequently asked questions
How much does it cost to run a space heater?
A typical 1,500-watt space heater run 5 hours a day at the US average residential rate (18.31¢/kWh, July 2026, EIA) costs about $1.37 a day, $41.20 a month, or $501 a year. Enter your own wattage, hours and local rate above for an exact estimate -- heaters range from about 750W to 1,500W.
How much electricity does a TV use?
A typical LED TV (~100 watts) run 5 hours a day uses about 0.5 kWh a day, or 15 kWh a month -- around $2.75 a month at the US average rate. Older or larger TVs (plasma, big-screen) can use 200-400+ watts; check your TV's label or manual for its actual rating.
How do I calculate electricity cost?
kWh = watts × hours ÷ 1000; cost = kWh × your rate per kWh. Example: a 1,500W space heater running 5 hours: 1,500 × 5 ÷ 1000 = 7.5 kWh, × 0.1831 = $1.37 for that day.
What's the average cost to run a refrigerator?
A refrigerator (a typical ~150W, running continuously) costs about $19.77 a month and $241 a year at the US average rate -- refrigerators vary a lot by size and age, so check your model's EnergyGuide label for its actual annual kWh estimate.
What electricity rate does this calculator use by default?
The default is the US average residential price of electricity, 18.31¢/kWh, from the U.S. Energy Information Administration's Electric Power Monthly (Table 5.6.A), July 2026 data (the most recent available; EIA's report lags about two months). This is a NATIONAL average -- actual rates vary widely by state and utility (EIA's own state table shows roughly 13-53 cents/kWh), so always replace it with the rate from your own electric bill for an accurate result.
Why doesn't this page have a table of electricity cost by state?
Rates change often and vary further within a state by utility and rate plan, and we'd rather not publish a stale or oversimplified table. Check your own utility bill or the EIA's state-level data (eia.gov) for your area's current rate, and enter it into the calculator above.
What is an appliance energy calculator?
A tool that estimates how much energy (kWh) and money a device uses from its wattage and how long you run it -- exactly what the "one appliance" mode above does. The "several appliances" mode adds up a checklist of common household appliances into a whole-home estimate.
Is kWh the same as kW?
No -- a kilowatt (kW) is a rate of power (1,000 watts), while a kilowatt-hour (kWh) is an amount of energy: a kW used for one hour. Your electric bill is priced per kWh, which is why this calculator multiplies watts (converted to kW) by hours to get the energy used.
Does this include fees, taxes or tiered rates?
No -- it multiplies your wattage, hours and a single rate per kWh, which is how most utilities bill the energy portion of your usage. Many utilities also add fixed monthly fees, taxes, delivery charges or tiered/time-of-use rates that increase per kWh at higher usage, none of which are modeled here. Use this as an estimate of the usage-based cost, and check your actual bill for the full picture.
Is my data saved or sent anywhere?
Your entries are saved only in your own browser so they are there next time. Nothing is sent to our servers.