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Sumivo · Electrical

Electricity Cost Calculator

Estimate daily energy use and cost from power, runtime, and your electricity rate.

01 / INPUTS

W
h/day
/kWh

02 / RESULT

30-DAY COST

45

Energy per day
10 kWh
Cost per day
1.5
Cost per 30 days
45

Calculation trace

  1. (1,000 W ÷ 1000) × 10 h = 10 kWh
    10 kWh
    Daily energy
  2. 10 kWh × 0.15 per kWh = 1.5
    1.5
    Daily cost
  3. 1.5 × 30 days = 45
    45
    30-day cost
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How it works

The tool converts watts to kilowatts, multiplies by the hours of use to get energy in kilowatt-hours (kWh), then multiplies by your rate per kWh. Daily energy = (watts ÷ 1000) × hours per day; daily cost = daily energy × rate; 30-day cost = daily cost × 30. For example, a 1,000 W load running 10 hours a day uses (1000 ÷ 1000) × 10 = 10 kWh a day; at a rate of 0.15 per kWh that is 1.50 a day and 45.00 over 30 days. A 60 W lamp on for 5 hours at 0.20 per kWh uses 0.3 kWh and costs 0.06 a day, or 1.80 over 30 days. The cost of one hour is simply kilowatts × rate, so 1 kW at 0.15 per kWh costs 0.15 an hour. If you already know your energy in kilowatt-hours, from a bill or a meter, you do not need watts or hours: cost = kWh × rate, so 1,000 kWh at 0.15 is 150.00 and 2,700 kWh at 0.15 is 405.00. The 0.15 rate in these examples is only an illustration; use your own.

Assumptions & limits

  • The rate per kWh is whatever you enter, in your own currency. The tool has no built-in tariffs and does not look up local prices.
  • Power is the average real power the device draws while it runs, in watts, not volt-amperes. A nameplate rating is often a maximum, and a device with a thermostat or a motor cycles on and off, so its average draw can be lower than the label.
  • Hours per day must be greater than 0 and at most 24; the tool prices one steady daily pattern.
  • A month is approximated as 30 days. For a billing period with a different number of days, multiply the daily cost by that number.
  • Only the energy charge is calculated. Fixed monthly charges, delivery or demand charges, taxes, tiered or time-of-use rates, and standby draw outside the hours you enter are not included.
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FAQ

How do I calculate the cost of electricity for an appliance?
Convert its power to kilowatts (watts ÷ 1000), multiply by the hours it runs to get kWh, then multiply by your price per kWh. A 1,000 W heater that runs 10 hours a day uses 10 kWh a day; at 0.15 per kWh that costs 1.50 a day. Enter the watts, hours per day and your rate above and the tool shows each step.
How much does 1 kWh of electricity cost?
It depends on your country, utility and plan, so this tool does not assume a price. Look for the price per kWh on your bill or tariff sheet, or divide the energy-related charges on a bill by the kWh used, and enter that figure as the rate.
How do I convert kWh to cost?
Multiply the kWh by your rate: cost = kWh × price per kWh. For example, 1,000 kWh at 0.15 per kWh is 150.00, and 2,700 kWh at 0.15 is 405.00 (0.15 is only an illustration). This calculator takes watts and hours, so to price a kWh figure here, enter 1,000 W for 1 hour, which is exactly 1 kWh, and multiply the daily cost shown by your kWh.
How much does it cost to run something per hour?
Cost per hour = kilowatts × rate. A 1,500 W device is 1.5 kW, so at 0.12 per kWh it costs 1.5 × 0.12 = 0.18 for each hour it runs at that power. For 1 kW the hourly cost equals the rate itself.
How do I estimate a full year of electricity cost?
Multiply the daily cost by 365 if the device is used every day. Multiplying the 30-day figure by 12 covers only 360 days, so it slightly underestimates a full year. If the device runs only some days, multiply the daily cost by the number of days it is actually used.
Why is my electricity bill higher than the estimate?
The estimate covers one device and the energy charge only. A bill usually adds fixed charges, delivery or demand charges and taxes, and many plans use tiered or time-of-use rates. The device may also draw more than the wattage you entered, or use standby power when it is not running.
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