EV Charging Cost & Time Calculator
Calculate the cost and time to charge an electric vehicle from any state of charge to any target, at any kW charger speed and electricity rate.
What this calculates
EVs charge from any power source — slow home Level 1 outlets, fast Level 2 stations, or DC fast chargers — at very different speeds and prices. This calculator estimates the time and cost to add a specific number of kWh given the charger speed, your electricity rate, and a typical 10 % loss during charging.
Formula & how it works
Energy needed = (target_pct − current_pct) ÷ 100 × battery_kWh. Time = energy ÷ charger_kW (DC fast chargers throttle near 100 %, this estimate is for the bulk 10-80 % range). Cost = (energy ÷ 0.9 efficiency) × price_per_kWh. The 10 % efficiency loss accounts for AC-to-DC conversion and battery thermal management.
Worked example
75 kWh battery from 20 % to 80 % (60 % of 75 = 45 kWh). At a 150 kW DC fast charger: time ≈ 45 ÷ 150 = 0.30 hr = 18 minutes (real-world ~22-25 with throttling). Cost at $0.50/kWh public rate: 45 / 0.9 × 0.50 = $25.00. Same charge at home overnight (7 kW, $0.15/kWh): 6.4 hours, $7.50.
Frequently asked questions
Why do public chargers cost more?
Higher kW costs more infrastructure, plus demand charges from the utility, plus operator profit. Home L2 is almost always cheapest. Some workplaces offer free charging. Tesla Supercharger rates ($0.30-0.50/kWh) are typically lower than third-party stations.
Is 80 % a soft limit?
Yes for daily use — extends battery life. DC fast chargers slow dramatically above 80 % to protect cells. For road trips, charge 10-80 % at each stop, not 0-100 %.
How does cold affect charging?
A lot. Below 0 °C, charging speed drops 30-50 % until the battery warms. Many EVs pre-condition the battery if you navigate to a charger. Plan extra time in winter trips.
Per-mile cost vs gas?
Average EV: 3-4 miles per kWh. At $0.15/kWh home rate: 4 cents/mile. Gas car at 30 MPG, $4/gallon: 13 cents/mile. EV typically 50-70 % cheaper. Public charging narrows the gap.