Use the schedule attached to your account
The EIA explains that some utilities offer time-of-day prices. That does not mean every customer has them, or that every utility uses the same peak hours. Check the current tariff for your specific account, including its season, weekday and weekend rules.
Write down the complete applicable per-kWh charge for each period. If supply and delivery are listed separately, determine which components change with the time band. Keep fixed fees outside an individual appliance’s incremental cost calculation, but include them when comparing whole electricity plans.
Split one appliance into two periods
Imagine an appliance uses 3 kWh during an off-peak band priced at $0.12/kWh and 2 kWh during a peak band at $0.30/kWh. These prices are invented for the example, not a current utility offer.
| Period | Energy | Cost |
|---|---|---|
| Off-peak at $0.12/kWh | 3 kWh | $0.36 |
| Peak at $0.30/kWh | 2 kWh | $0.60 |
| Total | 5 kWh | $0.96 |
The usage-weighted rate is $0.96 ÷ 5 = $0.192/kWh. Averaging the two prices gives $0.21, which would incorrectly price the same use at $1.05. Energy weighting makes the difference.
Calculate a possible shift, not a promised saving
If 1 kWh can move from the example peak band to the off-peak band, with no change in total energy, the saving is 1 × ($0.30 − $0.12) = $0.18. Repeating that shift on 20 days would save $3.60.
This assumes the appliance still performs the same job using the same total energy. Changing a cooling schedule can change the amount of energy required, so moving the clock alone is not enough to establish the result. Choose schedules that suit the appliance instructions and household needs.
Use the calculator one band at a time
The running cost calculator accepts one rate per calculation. Calculate the hours that belong to the first band, record that result, then calculate the second band and add them. Avoid applying both prices to the full operating period.
A whole-plan decision needs all household use, fees and tariff conditions. Saving on one flexible appliance does not show that the plan will lower your total bill. If available, use your utility’s interval history or plan comparison to check the broader pattern before switching.
Choose your next step
Continue with the question that matches your next decision:
Sources & further reading
Numerical examples are illustrative unless explicitly described as measured. This guide does not claim hands-on product testing. Read the methodology and editorial disclosure.