Watts to kWh: Calculate Energy and Cost
Divide watts by 1,000 and multiply by hours to get kWh. If watts are a full-power rating, also account for cycling. If watts are already a measured average, use them directly.
Understand and estimate your electricity costs
Work through energy units, meter readings, rate plans and appliance labels with explicit examples you can adapt to your own bill.
Individual appliance estimates · State rate data · Appliance comparisons
Time-of-Use Electricity Cost: Worked Example
Price each block of electricity at the rate applying when it was used, then add the results. A simple average of peak and off-peak rates works only when equal energy is used in those periods.
Electric Bills: Fixed vs Variable Charges
Dividing your bill by kWh gives an average paid price, but that is not always the value of saving one more kWh. Separate charges tied to usage from charges that remain when usage falls.
Standby Power Cost: Calculate Idle Energy
A small load can accumulate energy when it remains connected for long periods. Measure the actual low-power mode and count only the hours spent in that mode before estimating a yearly cost.
Measure Appliance Electricity in kWh
An accumulated kWh reading captures changes in power during the measurement period. Record the elapsed time and operating conditions, then scale only as far as those conditions remain representative.
Read EnergyGuide Labels and Reprice kWh
Start with the energy figure and the comparison category on the label. The annual dollar estimate uses a stated set of assumptions; your household price and usage may be different.