A time-of-use (TOU) electricity calculator shows how much you can save by running high-wattage appliances during off-peak hours when electricity rates are lowest. TOU pricing plans are now available from most major US utilities — and with EVs, smart appliances, and home batteries becoming mainstream, shifting your usage can save $30–$100+ per month.
Rate Plan
e.g., 4–9 PM weekdays
e.g., 9 AM–4 PM weekdays
e.g., 9 PM–9 AM + weekends
Appliances & Usage Schedule
Set each appliance's wattage, how many hours/day it runs, and what time it currently starts. Then see the best time to shift it to save money.
How to Use the Time-of-Use Calculator
Time-of-use electricity pricing is expanding rapidly across the US — California, New York, Texas, Illinois, and dozens of other states now offer TOU rate plans. Unlike flat-rate pricing, TOU rates charge more during peak demand hours (typically 4–9 PM on weekdays) and significantly less during off-peak hours (nights and weekends). This time-of-use calculator shows you exactly how much you can save by shifting your biggest energy loads to off-peak windows.
Step 1: Select Your Utility or Enter Rates
Choose your utility's TOU plan from the preset list — SCE TOU-D, PG&E E-TOU-C, SDG&E, ConEd, and others are included with their actual published rates. If your utility isn't listed or you want to compare a hypothetical plan, select "Custom" and enter your peak, mid-peak, and off-peak rates in $/kWh from your bill or utility website. The 24-hour rate schedule timeline updates automatically to show when each rate period applies.
Step 2: Add Your Appliances
Click "Add Appliance" to add each high-wattage device in your home. For each one, set its wattage (check the nameplate or use the presets), how many hours per day it typically runs, how many days per week, and the hour it currently starts. Common TOU-impactful appliances include: EV charger (7,200W), electric dryer (5,000W), dishwasher (1,400W), washing machine (700W), pool pump (1,500W), and window AC units (1,200W).
Step 3: Calculate and Review Savings
Click "Calculate TOU Savings" to see your current monthly electricity cost for these appliances and what you'd pay if you shifted them to the cheapest available hours. The results table shows the recommended start time for each appliance and the monthly savings from making that shift. The total monthly and annual savings figures give you a clear picture of TOU plan value for your household.
Understanding the Rate Timeline
The color-coded 24-hour timeline shows when each rate period applies on a typical weekday. Red indicates peak pricing, amber shows mid-peak, and green marks the cheapest off-peak hours. Most utilities apply off-peak rates all day on weekends and holidays — this timeline reflects weekday pricing only. Check your utility's specific rate schedule for seasonal variations (summer vs. winter peak hours often differ).
When TOU Plans Save the Most
Time-of-use plans deliver the biggest savings for households with: (1) an electric vehicle — even charging at home overnight saves $40–$80/month vs. peak charging, (2) flexible scheduling for laundry and dishwashing, (3) a pool or hot tub with a pump that can run at night, or (4) a smart thermostat that can pre-cool before 4 PM. If you work from home and use lots of electricity during the day, or run medical equipment continuously, a flat-rate plan may still be better — use this calculator to compare both scenarios.
How TOU Cost Is Calculated
For each appliance, the calculator determines which rate period(s) its usage window falls into during each hour of operation. It then multiplies the wattage by the hours in each rate period and the corresponding $/kWh rate to compute daily cost, then scales to a monthly estimate (30.44 days/month average). The optimized cost shifts each appliance to the lowest-cost available window that fits its runtime duration, finding the best off-peak or mid-peak slot for each device.
FAQ
Is this time-of-use calculator free?
Yes, completely free with no signup required. Enter your rate plan rates and appliance schedules, and the calculator instantly shows your current and optimized monthly costs. All calculations run locally in your browser — no data is ever sent to a server.
Is my data private when I use this tool?
Absolutely. All calculations run entirely in your browser using JavaScript. No rate plan details, appliance lists, or usage schedules are transmitted anywhere. You can even use it offline once the page loads.
What is a time-of-use (TOU) rate plan?
A time-of-use rate plan charges different prices for electricity depending on the time of day and sometimes the season. Peak hours (typically 4–9 PM on weekdays) cost more because demand is highest. Off-peak hours (nights, early mornings, and weekends) are cheaper. Shifting energy-intensive tasks like laundry, dishwashing, and EV charging to off-peak periods can significantly reduce your bill.
Which appliances save the most money when shifted to off-peak hours?
High-wattage appliances with flexible timing save the most: electric vehicle chargers (7,200W+), electric dryers (5,000W), dishwashers (1,200–1,500W), washing machines (500–1,000W), and pool pumps (750–2,500W). Running these during off-peak hours instead of peak hours can save $20–$80+ per month depending on your rate differential and usage frequency.
How much can I save with a TOU rate plan?
Savings vary widely by utility, rate plan, and usage habits. Households with EVs or high daytime electricity use often save $30–$100+ per month by shifting to TOU plans. However, if most of your usage is already in the evenings when peak rates apply, a flat-rate plan may actually be cheaper. Use this calculator to compare your specific situation before switching.
What are typical peak, mid-peak, and off-peak hours?
Most TOU plans define peak hours as 4–9 PM on weekdays (when the grid is most stressed). Mid-peak typically covers daytime hours like 9 AM–4 PM. Off-peak hours are nights (9 PM–9 AM) and all day weekends and holidays. Rates can differ by utility and season — check your specific utility's rate schedule for exact hours.
Does TOU pricing apply on weekends?
Most utility TOU plans treat weekends and holidays as off-peak, all day. This makes weekends ideal for running high-wattage appliances without extra cost. Some utilities like PG&E E-TOU-C apply off-peak rates all weekend, making it one of the best times to do laundry, run the dishwasher, and charge an EV.
Should I switch to a TOU rate plan?
TOU plans benefit households that can shift usage away from peak hours — especially those with EVs, smart appliances, or flexible work schedules. They tend to hurt households with fixed daytime usage (e.g., working from home, medical equipment needs). Run both scenarios through this calculator using your utility's flat rate vs TOU rates to see which saves more before contacting your utility to switch.