Per-kWh vs Per-Minute Charging Price Calculator
Some public chargers bill by energy, others by time. Compare a session both ways using your car's average charging power.
How it works
Minutes = energy ÷ average power × 60. Per-kWh cost = energy × price per kWh (+ session fee). Per-minute cost = minutes × price per minute (+ session fee). Break-even per-minute price = price per kWh × average kW ÷ 60.
Worked example: 40 kWh at an average 80 kW takes 30 minutes. Per-kWh at $0.45 = $18.00; per-minute at $0.50 = $15.00. Break-even = 0.45 × 80 ÷ 60 = $0.60 per minute.
Assumptions
- Use average power over the session, not the charger's peak rating. Charging slows as the battery fills (U.S. DOT), so the average is usually lower than the peak.
- Some networks use tiered per-minute prices by power level, memberships or idle fees; these are not modeled.
- The same session fee is applied to both options.
- All prices are editable estimates. The defaults are placeholders, not current market prices; use your own bill or charger's posted price.
Frequently asked questions
Why do some chargers bill per minute?
The DOE Alternative Fuels Data Center says session- and time-based pricing structures are common in states where non-utilities are prohibited from selling electricity.
When is per-minute billing cheaper?
When your car charges fast. Per-minute pricing costs less than per-kWh pricing whenever the per-minute price is below price per kWh × average kW ÷ 60.
Related calculators
- EV road trip charging cost calculator
- EV charging time calculator
- Cost to charge an EV battery from X% to Y%
- EV charger power and miles-per-hour calculator
Sources
Formulas and reference values are from these sources. Page last reviewed 2026-10-19.