kWh calculator (watts to kWh)
See how much an air conditioner, water heater or fridge uses in a month before the bill arrives.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter device power, hours of use per day, number of days and price per kwh (optional).
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Daily kWh = watts × hours ÷ 1000, total = daily × days, cost = total × price per kWh.
Example
Inputs: Device power = 1,500 W, Hours of use per day = 8 h, Number of days = 30 days, Price per kWh (optional) = 0.18. Result: Total energy: 360 kWh; Daily energy: 12 kWh; Estimated cost: 64.80.
Limits and caveats
- Compressor appliances such as air conditioners and fridges do not run at full power all the time; the result is an upper bound unless you enter actual running hours.
- Many utilities charge tiered rates; a single price here is an approximation.
Questions about this tool
How much does a 1500 W air conditioner use at 8 hours a day?
12 kWh per day, or 360 kWh over 30 days if it runs at full power.
What is the difference between watts and kWh?
Watts are instantaneous power; kWh is energy over time. A 1000 W device running for one hour uses 1 kWh.
Where do I find the price per kWh?
On your electricity bill or your utility’s website. Enter it in your local currency to see the cost in it.