EV Charging Calculator
Estimate EV charging time and cost: enter battery size, charge level, charger speed, and your electricity rate.
How long will it take to charge your EV, and what will it cost? Enter your battery size in kWh, the charge range (e.g. 20% to 80%), your charger's power in kW, and your electricity rate to get charging time, energy added, and cost per charge — plus miles per dollar if you know your efficiency.
Home ~7–11 kW · public DC fast 50–350 kW
How to use this calculator
- Enter your EV's battery size in kWh (check the spec sheet).
- Enter the charge range, e.g. 20% to 80%.
- Enter your charger's power in kW and your electricity rate per kWh.
- Optionally enter your efficiency (mi/kWh) for miles-per-dollar, then press Calculate.
The formula
Energy = battery × (to% − from%) ÷ 100; time = energy ÷ charger kW; cost = energy × rate
Worked example
Charging a 75 kWh battery from 20% to 80% adds 45 kWh. On an 11 kW home charger at $0.15/kWh, that's 4 hours 5 minutes and $6.75.
Frequently Asked Questions
How long does it take to charge an electric car?
It depends on how much energy you need and your charger's power: time ≈ kWh needed ÷ kW. A 75 kWh battery charging from 20% to 80% needs 45 kWh, which takes about 4 hours on an 11 kW home charger but roughly 20 minutes on a 150 kW DC fast charger. Real charging slows near full, so the last 20% always takes disproportionately longer.
How much does it cost to charge an EV at home?
Multiply the kWh you add by your electricity rate. Adding 45 kWh at $0.15/kWh costs $6.75 — typically a third to a quarter of the equivalent gasoline cost. Many utilities offer cheaper overnight EV rates, so check your rate plan; charging at 2 AM can be half the price of charging at 6 PM.
What do kW and kWh mean?
kW (kilowatts) is power — how fast energy flows, like the width of a hose. kWh (kilowatt-hours) is energy — how much is stored, like the amount of water in a bucket. Your charger is rated in kW and your battery in kWh; dividing energy by power gives charging time.
Why shouldn't I charge to 100% every day?
Lithium batteries degrade faster when held at very high or very low charge for long periods, and charging slows dramatically above 80% as the battery management system protects the cells. Most manufacturers recommend a daily limit of 80–90% and saving 100% charges for road-trip days. This calculator assumes a constant rate, so treat near-full estimates as optimistic.
Is charging an EV cheaper than gas?
Almost always, yes — especially at home. At $0.15/kWh and 3.5 mi/kWh, you're paying about 4 cents per mile, versus 12–16 cents per mile for a 25 MPG gas car at $3.50/gallon. Public fast charging costs more (often $0.40–$0.60/kWh) but is still usually cheaper than gas for the same miles.