The single rate on your flat plan.
The time-of-use rate during peak hours.
The time-of-use rate during off-peak hours.
Total kWh from a recent bill.
Share of your use that falls in peak hours today.
kWh you could move from peak to off-peak each month.
Enter your flat rate, peak and off-peak rates, monthly use, your current peak share, and how much load you can shift to see the break-even shift and estimated monthly savings or penalty.
Rates vary by utility and tariff and change over time. Verify peak windows and rates against your own utility tariff before you rely on a result. Reviewed 2026-06.
About the time-of-use rate breakeven calculator
The time-of-use rate breakeven calculator compares a flat single-rate electric plan with a time-of-use plan that charges more during peak hours and less off peak. Enter your flat rate, the peak and off-peak rates, your monthly use, the share of use that falls in peak hours today, and how much load you think you can move off peak. The tool returns the percent of use that must shift to break even and the estimated monthly savings or penalty.
Time-of-use plans only save money if you can move enough use out of the expensive peak window. This is a planning estimate, not utility, financial, or legal advice. Rates and peak windows vary by utility and tariff and change over time, so confirm them against your own bill or rate sheet and the EIA consumer guidance the tool links to.
How to use
- Enter your flat plan rate in dollars per kWh.
- Enter the time-of-use peak and off-peak rates in dollars per kWh.
- Enter your monthly use in kWh from a recent bill.
- Enter the share of that use that currently falls in peak hours.
- Enter how many kWh you could move from peak to off-peak each month.
- Select Compare plans to see the break-even shift and your estimated monthly savings or penalty.
Worked examples
A small break-even shift means time-of-use is easy to win
When only a few percent of monthly use must move off peak, a time-of-use plan can save money with modest changes.
A penalty means time-of-use costs more after your planned shift
If you cannot move enough load off peak, the time-of-use bill can be higher than the flat plan.
An unreachable break-even means the flat plan likely wins
When the break-even needs more shift than the load you actually have in peak hours, time-of-use cannot match the flat plan at those rates.
Frequently asked questions
- How does the break-even shift work?
- The calculator finds the share of your monthly use that must move from peak to off-peak hours for the time-of-use bill to equal your flat plan bill. A smaller break-even shift is easier to reach.
- Why does it show a penalty instead of savings?
- If the load you can shift off peak is not enough to overcome the higher peak rate, the time-of-use bill ends up above your flat plan bill. The tool shows that gap as an estimated monthly penalty.
- What if my peak and off-peak rates are the same?
- Then shifting load does not change the time-of-use bill, so there is no break-even shift. The tool says so instead of showing a percentage.
- Is this official rate advice?
- No. This is a free planning estimate to help you compare plans. It does not quote a tariff, enroll you in a plan, or replace your utility's rate sheet and the EIA consumer guidance the result panel links to.
- Do you store the rates or usage I enter?
- No. The calculation runs entirely in your browser. Your rates and usage are not saved or sent to a server, and the tool collects no utility account, address, meter id, or bill upload.
- Does it work on mobile?
- Yes. The calculator is built to work on phones and desktops.
- Is the time-of-use rate breakeven calculator free?
- Yes. It is free to use and does not require an account.
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