The EV charging cost calculator answers the question most new EV buyers can't find a clean answer to: not "what does electricity cost?" but "what will I actually pay per month to charge this specific car, with my specific mix of home and public charging, on my utility's specific rate schedule?" The answer varies by 3× or more depending on those inputs — which is exactly why a personalized calculation matters more than any national average.

This page exposes every step of the calculation. If you find a discrepancy between our formula and your real-world bills, write us. Understanding where the gap comes from is usually instructive.

The formula

The core calculation is a weighted-average per-kWh cost across three charging tiers, applied to annual kWh consumption.

annual_kwh = (annual_miles ÷ 100) × kWh_per_100mi home_kwh = annual_kwh × (pct_home ÷ 100) l2_kwh = annual_kwh × (pct_l2 ÷ 100) dcfc_kwh = annual_kwh × (pct_dcfc ÷ 100) annual_cost = (home_kwh × home_rate) + (l2_kwh × l2_rate) + (dcfc_kwh × dcfc_rate) per_mile_cost = annual_cost ÷ annual_miles

The TOU adjustment modifies the home tier. When a TOU off-peak rate is entered, the home charging cost becomes:

home_tou_cost = home_kwh × [(pct_tou_offpeak ÷ 100) × tou_rate + (1 − pct_tou_offpeak ÷ 100) × home_rate] tou_savings = home_kwh × (home_rate − home_tou_cost ÷ home_kwh)

EPA kWh/100mi as the efficiency input

We use EPA-rated kWh per 100 miles as the efficiency basis, not manufacturer range claims or MPGe (Miles Per Gallon equivalent). Here is why:

  • kWh/100mi maps directly to cost: Multiply by your electricity rate in $/kWh and you have cost per 100 miles. The arithmetic is transparent and verifiable.
  • EPA ratings are standardized: EPA tests all vehicles on the same standardized 5-cycle test procedure, making the figures comparable across models.
  • Real-world consumption typically runs 10–20% higher than EPA: Cold weather, highway speeds above 70 MPH, aggressive acceleration, and HVAC use all increase kWh/100mi above the EPA figure. Our calculator uses EPA figures for consistency; users who drive predominantly at highway speeds in cold climates should increase the kWh/100mi input by 10–20% to get a more realistic cost estimate.

The charging mix assumption

The three charging percentage inputs (home, public Level 2, DC fast) must sum to 100%. The default split of 80/15/5 reflects survey data from ChargePoint and the Edison Electric Institute showing that US EV owners do approximately 80% of their charging at home, 15% at public Level 2, and 5% at DC fast chargers.

This default is not right for everyone:

  • Apartment or condo residents without home charging: May be 0% home, 100% public — dramatically increasing per-mile cost. A car charged entirely on commercial L2 at $0.35/kWh costs 3–4× more per mile than one charged at home at $0.12/kWh.
  • Long-haul commuters with employer charging: If your employer provides free Level 2, set that portion's rate to $0.00 — the calculator handles that input. The effective per-mile cost drops significantly.
  • Road-trip-heavy users: One 500-mile road trip per month at DC fast charge rates ($0.45/kWh) adds roughly $100–$130/year to annual charging cost versus zero DCFC. Not negligible but rarely dominant unless road trips are very frequent.

Time-of-use rate methodology

The TOU calculation models the savings from shifting home charging to off-peak hours. The formula assumes you charge only the specified percentage of home charging at the off-peak rate, and the remainder at your flat daytime rate. In practice, a smart EVSE with a scheduled departure time can push 90–100% of charging to the off-peak window on most nights, making the full off-peak rate achievable for nearly all home charging.

The TOU savings output is the difference between your total home charging cost at the flat rate versus the blended home charging cost with the specified off-peak percentage. It does not include any utility TOU plan enrollment fees or meter upgrade costs, which are one-time capital items.

What's excluded

  • Charging losses: The AC-to-DC conversion in the onboard charger and resistance in the cable and charging equipment mean the wall consumption is 10–15% higher than the vehicle's reported kWh/100mi figure. We use EPA figures unadjusted for consistency with the rest of the site's methodology.
  • Home charger installation cost: One-time capital expenditure, not a recurring operating cost. See the charger installation guide for that analysis.
  • Public charging session fees: Some networks charge per-session connection fees ($1–$2) in addition to per-kWh rates. If your network charges session fees, add them to your effective per-kWh rate manually: (session fee ÷ average kWh per session) + per-kWh rate.
  • Demand charges: Some commercial-rate electricity tariffs include a demand charge based on peak draw. Residential rates typically don't have demand charges, but a small number of US utilities have experimental demand-based residential EV rates. We model $/kWh rates only.

A worked example — Pacific Northwest

2026 Hyundai IONIQ 5 Standard Range (28 kWh/100mi EPA), 14,000 miles/year. Washington State. Charging mix: 85% home, 10% public L2, 5% DCFC. Home electricity rate: $0.099/kWh (Puget Sound Energy typical residential). TOU off-peak rate: $0.066/kWh (PSE EV Advantage plan), 90% of home charging in off-peak window. Public L2: $0.28/kWh (ChargePoint). DCFC: $0.43/kWh (Electrify America).

annual_kwh = (14,000 ÷ 100) × 28 = 3,920 kWh home_kwh = 3,920 × 0.85 = 3,332 kWh l2_kwh = 3,920 × 0.10 = 392 kWh dcfc_kwh = 3,920 × 0.05 = 196 kWh home_tou_cost = 3,332 × (0.90 × $0.066 + 0.10 × $0.099) = $231 l2_cost = 392 × $0.28 = $110 dcfc_cost = 196 × $0.43 = $84 annual_total = $231 + $110 + $84 = $425 per_mile = $425 ÷ 14,000 = $0.030/mile

At $0.030/mile for electricity, compared to a 30 MPG gas car at $3.25/gallon ($0.108/mile), this driver saves $0.078/mile — or $1,092/year — purely on fuel. Washington's cheap electricity and TOU off-peak plan are doing substantial work here. TOU savings versus all-flat-rate home charging: (3,332 × $0.099) − $231 = $330 − $231 = $99/year saved from TOU alone.

Sources and update cadence

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