Time-of-Use Rate Calculator

About the Time-of-Use Rate Calculator

Time-of-use (TOU) pricing is an electricity billing structure where the rate per kWh varies by time of day. Peak hours (typically 2–7 PM on weekdays) have the highest rates, mid-peak hours have moderate rates, and off-peak hours (nights and weekends) have the lowest rates. The difference between peak and off-peak can be 2–5 times.

TOU pricing encourages consumers to shift electricity use to off-peak hours, reducing strain on the power grid during high-demand periods. Common ways to save include running laundry, dishwashers, and EV chargers during off-peak hours. Smart home devices and programmable thermostats can automate this shifting.

This calculator lets you enter your kWh usage and rate for each TOU period to calculate your total bill. Compare your TOU bill against a flat-rate plan to determine which pricing structure saves you money based on your usage patterns.

Understanding this metric in precise terms allows energy managers to evaluate investment options, forecast savings, and build compelling business cases for efficiency upgrades and retrofits.

When This Page Helps

TOU plans can save or cost money depending on when you use electricity. This calculator shows your total bill across all rate periods and helps you evaluate whether shifting usage to off-peak hours is worthwhile. Having accurate metrics readily available streamlines utility bill analysis, budget forecasting, and investment planning for energy efficiency projects and renewable energy installations.

How to Use the Inputs

1. Enter the kWh consumed during the peak period and the peak rate.
2. Enter the kWh consumed during the mid-peak period and its rate.
3. Enter the kWh consumed during the off-peak period and its rate.
4. View the cost for each period and the total monthly bill.
5. Compare to a flat-rate cost for the same total kWh.
6. Adjust kWh between periods to model shifting scenarios.

Example Calculation

Tips & Best Practices

• Run dishwashers, laundry, and EV chargers during off-peak hours.
• Pre-cool your home before peak hours to reduce AC costs during expensive periods.
• Use a programmable thermostat to shift HVAC load to off-peak times.
• Pool pumps and water heaters can often be scheduled for off-peak operation.
• Check if your utility offers a TOU plan specifically for EV owners with very low overnight rates.
• Monitor your smart meter data to track usage by time period.

Understanding TOU Rate Structures

Most TOU plans have 2–3 rate periods: peak (most expensive), mid-peak (moderate), and off-peak (cheapest). Some plans add a "super off-peak" period (midnight–6 AM) with extremely low rates, ideal for EV charging. Summer and winter often have different rates and peak hours.

Best Candidates for TOU Plans

Households that benefit most from TOU pricing include: EV owners who can charge overnight, families where most usage happens in the evening/night, homes with programmable appliances, and those with home battery storage that can charge during off-peak and discharge during peak.

TOU and Solar Panels

Solar panel owners on TOU plans benefit when solar generation offsets peak-rate electricity. Since solar panels produce most electricity during afternoon peak hours, TOU plans can increase the value of solar by 20–40% compared to flat-rate plans.

Frequently Asked Questions

• What are typical TOU peak and off-peak rates?

  Peak rates range from $0.25–$0.55/kWh, mid-peak from $0.12–$0.22, and off-peak from $0.05–$0.12/kWh. The specific rates and hours vary by utility. Summer peak rates are usually higher than winter because of air conditioning demand.

• Is a TOU plan cheaper than a flat rate?

  It depends on your usage pattern. If you can shift 50%+ of your usage to off-peak hours, TOU is typically cheaper. If most of your usage occurs during peak hours (e.g., working from home with heavy AC), a flat rate may be better.

• When are peak hours?

  Peak hours are typically 2–7 PM or 4–9 PM on weekdays, when AC demand is highest. Some utilities have morning peaks too. Weekends and holidays are usually off-peak all day. Check your specific utility's schedule.

• Can I switch between TOU and flat rate plans?

  Most utilities allow you to switch once per year or more frequently. Some offer a one-month trial period for TOU plans. Check your utility's website for plan comparison tools that use your actual usage data.

• How much can I save by shifting to off-peak?

  Shifting 300–500 kWh/month from peak to off-peak can save $40–$100/month, depending on the rate differential. The biggest savings come from scheduling EV charging, laundry, and HVAC pre-conditioning during off-peak hours.

• Do smart thermostats help with TOU plans?

  Yes. Smart thermostats can pre-cool or pre-heat your home during off-peak hours and coast through peak hours, significantly reducing your peak-period HVAC costs. Some thermostats integrate directly with utility TOU schedules.