Quick answer
Energy (kWh) = watts × hours ÷ 1,000, and cost = kWh × price per kWh. A 1,500 W appliance used 2 hours a day at $0.15 per kWh uses 3 kWh and costs $0.45 a day, about $13.70 a month and $164.25 a year.
Enter the appliance's power in watts, the hours it runs each day and your electricity price. The calculator returns daily, monthly and yearly cost.
Related tools: Pool Fill Time Calculator: Hours to fill a pool at a flow rate. Wall Area Calculator: Wall area of a rectangular room after openings. Water Usage Calculator: Household water use from people and use per person.
How to use the Appliance Energy Cost Calculator
- Enter power (W) (above 0).
- Enter hours used per day (between 0 and 24).
- Enter electricity price ($ per kWh) (above 0).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Power | A number, in W | > 0 |
| Hours used per day | A number | > 0, ≤ 24 |
| Electricity price | A number, in $ per kWh | > 0 |
Formula and method
Formula
kWh = watts × hours ÷ 1000; cost = kWh × price
IEEE-754 double precision; shown to the decimals indicated.
Use the appliance's typical running power, which is often below its label rating.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Power = 1500; Hours used per day = 2; Electricity price = 0.15.
| Result | Value |
|---|---|
| Cost per day | $0.45 |
| Energy per day | 3 kWh |
| Cost per month (30.4375 days) | $13.70 |
| Cost per year (365 days) | $164.25 |
Example 2
Inputs: Power = 100; Hours used per day = 24; Electricity price = 0.12.
| Result | Value |
|---|---|
| Cost per day | $0.29 |
| Energy per day | 2.4 kWh |
| Cost per month (30.4375 days) | $8.77 |
| Cost per year (365 days) | $105.12 |
Example 3
Inputs: Power = 60; Hours used per day = 8; Electricity price = 0.3.
| Result | Value |
|---|---|
| Cost per day | $0.14 |
| Energy per day | 0.48 kWh |
| Cost per month (30.4375 days) | $4.38 |
| Cost per year (365 days) | $52.56 |
The first line is the headline result (cost per day). Below it the appliance Energy Cost Calculator lists energy per day, cost per month (30.4375 days) and cost per year (365 days), which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Finding the wattage
The label or manual lists watts, or volts and amps (multiply them). Devices with motors or heating elements cycle on and off, so a rated 1,500 W space heater under a thermostat may average much less than 1,500 W over the day.
Standby and the monthly figure
The month is 30.4375 days (365.25 ÷ 12), so the monthly cost is a yearly average, not a calendar month. Standby draw of a few watts is small per device but runs 24 hours a day: 5 W continuously is 43.8 kWh a year.
How the result changes with power
Holding every other input at the first worked example, this table changes only power. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Power | Cost per day | Energy per day | Cost per month (30.4375 days) |
|---|---|---|---|
| 750 | $0.22 | 1.5 kWh | $6.85 |
| 1500 | $0.45 | 3 kWh | $13.70 |
| 3000 | $0.90 | 6 kWh | $27.39 |
| 6000 | $1.80 | 12 kWh | $54.79 |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Power: entering "0" shows "Power must be greater than 0." beside that field and no result.
- Hours used per day: entering "25" shows "Hours used per day must be at most 24." beside that field and no result.
Choosing between the Appliance Energy Cost Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Pool Fill Time Calculator](/lifestyle/pool-fill-time-calculator/) | pool volume and flow rate | Fill time |
| [Wall Area Calculator](/lifestyle/wall-area-calculator/) | room length, room width and ceiling height | Wall area |
| [Water Usage Calculator](/lifestyle/water-usage-calculator/) | people, water per person per day and days | Water used |
| [Lighting Lumens Calculator](/lifestyle/lighting-lumens-calculator/) | room area and target light level | Lumens needed |
| [Room Area Calculator](/lifestyle/room-area-calculator/) | length and width | Room area |
Assumptions and limitations
- Prices vary by tariff and time of day
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for power and hours used per day to confirm this.
Frequently asked questions
What is my electricity rate?
It is on your bill in cents or dollars per kWh; add delivery charges if they are per kWh.
Does it include time-of-use rates?
No, it uses one price.
How can I measure actual use?
A plug-in power meter measures real consumption.
What does the Appliance Energy Cost Calculator calculate?
Electricity cost of running an appliance. It returns Cost per day, Energy per day, Cost per month (30.4375 days) and Cost per year (365 days).
What formula does the Appliance Energy Cost Calculator use?
kWh = watts × hours ÷ 1000; cost = kWh × price. Use the appliance's typical running power, which is often below its label rating.
What do I need to enter in the appliance Energy Cost Calculator?
You enter Power (W), Hours used per day and Electricity price ($ per kWh).
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Prices vary by tariff and time of day.
What is an example of a appliance Energy Cost result?
With power 1500, hours used per day 2 and electricity price 0.15, the cost per day is $0.45.
Related calculators
- Pool Fill Time Calculator — Hours to fill a pool at a flow rate.
- Wall Area Calculator — Wall area of a rectangular room after openings.
- Water Usage Calculator — Household water use from people and use per person.
- Lighting Lumens Calculator — Lumens needed for a room at a light level you choose.
- Room Area Calculator — Floor area of a rectangular room.
- Water Bill Calculator — Water bill from usage, rate and a base charge you enter.
- Circle Skirt Calculator — Waist radius and fabric needed for a full, half or quarter circle skirt.
Sources
- ISO 8601-1: Date and time, representations for information interchange (calendar dates, ordinal dates and week dates)
- Gregorian calendar reform, papal bull Inter gravissimas (1582): the leap-year rule used for all dates
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.