How to use the EV charging cost calculator
- Enter your car’s usable battery capacity in kWh (from the manual or the maker’s website).
- Enter the battery % now and the % you will charge to.
- Enter your electricity price per kWh — from your bill or the charger app.
- Check the charging efficiency and charger power. Add your car’s efficiency to see range and cost per 100 miles or km.
EV charging formulas
Energy added (kWh) = Battery kWh × (End % − Start %) Energy from grid = Energy added ÷ Charging efficiency Cost = Energy from grid × Price per kWh Charging time (h) ≈ Energy from grid ÷ Charger kW Range added = Energy added × miles (or km) per kWh
Worked example
A car with a 60 kWh battery charges from 20% to 80% at home on a 7.4 kW wallbox, at $0.15 per kWh and 90% efficiency:
- Energy added = 60 × 0.60 = 36 kWh
- From the grid = 36 ÷ 0.90 = 40 kWh
- Cost = 40 × $0.15 = $6.00
- Time ≈ 40 ÷ 7.4 = 5.4 hours
- At 4 miles per kWh: 144 miles added — about $4.17 per 100 miles
Charging cost for common battery sizes (20% → 80%, 90% efficiency)
| Battery | kWh from grid | at $0.15/kWh | at ₹8/kWh | at €0.30/kWh |
|---|---|---|---|---|
| 30 kWh | 20.0 | $3.00 | ₹160 | €6.00 |
| 40 kWh | 26.7 | $4.00 | ₹213 | €8.00 |
| 60 kWh | 40.0 | $6.00 | ₹320 | €12.00 |
| 75 kWh | 50.0 | $7.50 | ₹400 | €15.00 |
| 100 kWh | 66.7 | $10.00 | ₹533 | €20.00 |
Charger types and speeds
| Charger | Typical power | Adds per hour (≈4 mi/kWh) |
|---|---|---|
| Wall socket (Level 1 / 15 A plug) | 1.4–3.3 kW | 5–12 miles (8–19 km) |
| Home wallbox (Level 2) | 7–11 kW | 25–40 miles (40–65 km) |
| DC fast charger | 50–350 kW | 150+ miles (240+ km) |
Comparing with petrol or diesel
To compare running costs, work out the fuel cost per 100 miles or km for a similar petrol car: fuel price × (100 ÷ miles per gallon), or fuel price × litres per 100 km. For example, a car doing 30 mpg with fuel at $3.50 per gallon costs about $11.67 per 100 miles, compared with about $4.17 for the EV in the example above. Remember that public fast charging can cost several times the home rate, which narrows the gap on long trips.
Ways to cut charging costs
- Use an off-peak or EV tariff and schedule charging overnight.
- Charge at home where possible and use fast chargers only on trips.
- Precondition while plugged in so heating or cooling uses grid power, not battery range.
- Pair with solar panels to charge during the day for very little cost.