EV Charging Cost & Time Calculator
Estimate the total cost of charging your EV from one state of charge to another, including charging losses and any time-based (per-minute or idle) session fees that depend on charger speed.
Last updated: May 2026
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About this calculator
Charging cost has two parts: energy and time. The energy actually stored is batteryCapacity x (targetCharge - currentCharge) / 100. Because charging is not perfectly efficient, the energy you draw from the grid is that figure divided by the efficiency (chargingEfficiency / 100), and the energy cost is the grid energy times electricityRate. The time part matters because many public chargers bill per minute or charge idle fees: charging time equals grid energy divided by chargerPower (in kW), and multiplying by idleFeePerHour adds the time-based charge. Faster chargers (higher chargerPower) cut the time and therefore the time-based fee. Set the session fee to 0 for free home charging, where only the energy term applies.
How to use
To take a 75 kWh battery from 20% to 80% you need to store 75 x 60 / 100 = 45 kWh. At 90% charging efficiency you actually pull 45 / 0.9 = 50 kWh from the grid, costing 50 x $0.18 = $9.00 in electricity. On an 11 kW charger that takes 50 / 11 = about 4.5 hours; with a $6/hour session fee that adds 4.5 x $6 = about $27.30, for a total of roughly $36.30. On a fast 150 kW charger the same energy costs the same $9.00 but the time fee almost disappears.
Frequently asked questions
How much does it cost to charge an electric car from 20 to 80 percent?
It depends on your battery size and electricity rate. The energy needed is the battery capacity times the percentage gained, divided by charging efficiency. For a 75 kWh battery going 20% to 80% at $0.18/kWh and 90% efficiency, the electricity alone is about $9. Public chargers may add per-minute or idle fees on top, which this calculator includes through the charger power and session fee fields.
Why does charging efficiency change how much I pay?
No charger transfers energy perfectly; some is lost as heat in the charger, cables, and battery. Typical AC home charging is around 85 to 90% efficient, so to put 45 kWh into the battery you actually buy about 50 kWh from the grid. Lower efficiency means you pay for more kWh than end up in the pack, which is why the efficiency field directly scales your electricity cost upward.
Does a faster EV charger cost more or less money?
For pure energy cost, charger speed makes no difference: the same kWh costs the same. But when a station bills by the minute or charges idle fees, a faster charger finishes sooner and racks up far smaller time-based charges. That is why this calculator uses charger power to compute the session time and then applies the time-based fee, so higher kW chargers can actually lower your total at per-minute stations.