EV Time-of-Use Charging Cost Calculator

Time-of-Use (TOU) Charging Cost

TOU rates charge different prices for electricity at different hours. EV owners can save 30-60% by shifting all charging to off-peak windows — usually overnight.

Typical TOU rate structures (US averages, 2026):

EV-specific plans such as PG&E’s EV2-A or Southern California Edison’s TOU-D-PRIME usually push the overnight window lower still, into the $0.06 to $0.10 range, and often move the peak window later in the evening. Terms differ by utility and change often, so read the current tariff sheet rather than trusting any summary, including this one.

The cost calculation: Cost = energy drawn from the grid (kWh) × rate ($/kWh)

Charging losses come first

Roughly 13% of what your meter records never reaches the battery, lost as heat in the on-board charger. That is grid-to-battery loss, not anything to do with the drivetrain, and it is the figure your utility bills you for. This calculator adds it before applying any rate, which is why the from-grid number below is larger than the battery number.

For a typical EV at 15,000 miles a year and 3.5 mi/kWh:

• Energy into the battery: about 4,300 kWh a year, or 360 kWh a month
• Drawn from the grid at 13% loss: about 405 kWh a month
• All at peak ($0.40): $162 a month
• All off-peak ($0.10): $41 a month
• Difference: $121 a month, or about $1,450 a year

That gap is why utilities bother offering these plans at all. Charging overnight moves load off the evening peak, which is worth more to the grid operator than the discount costs them.

TOU plan switching considerations:

• Most utilities allow free switching once or twice a year
• Verify your other usage (HVAC, water heater) isn’t penalized by peak rates
• Some utilities offer EV-only TOU as a separate sub-meter (cheap)
• Call utility — most won’t tell you about EV plans unless asked

Flat rate or time-of-use?

The honest answer depends on the rest of the house, not the car. Shift 80% or more of your charging overnight and the EV side of the bill drops sharply. But a household running air conditioning hard through the 4 to 9 PM peak can lose more on that than it gains on the car, because a TOU tariff prices everything by the hour, not just the charger. Most utilities let you switch back once or twice a year, so running a few months on each and comparing the bills is a better test than any estimate.

Smart-charging features:

• All major EVs have schedule/depart-by features (Tesla, Bolt, Mach-E, etc.)
• Home charger TOU integration (Wallbox, ChargePoint Home Flex, Emporia)
• Some utilities offer rebates for installing smart chargers