EV Charger Calculator
Calculate the charging time of an electric car from any station: 230 V socket, 3.7–22 kW Wallbox, fast DC stations. Size the breaker, RCD (type A) and cable for a home charging station.
What the calculator computes
- Full charge time from a socket, Wallbox and fast station
- Charging current by phase (1-phase and 3-phase charging)
- Circuit breaker, type A RCD and cable section for a home charging station
- Check of remaining house power (whether charging exceeds the allocated capacity)
- Charging cost by tariff (day/night)
- Charging losses (charger efficiency 85–90%)
How to calculate charging time
Charging time: t = E_battery × (SoC_final − SoC_initial) / (P_charge × η), where E is the battery capacity (kWh), P is the charging station power (kW), η is the efficiency of the onboard charger (0.88–0.92 for AC charging, 0.93–0.97 for DC).
Example: Tesla Model Y (60 kWh), charging 20→80% = 60 × 0.6 = 36 kWh. From an 11 kW Wallbox (3-phase, η = 0.9): t = 36 / (11 × 0.9) = 3.6 hours. From a 2.3 kW socket: t = 36 / (2.3 × 0.9) = 17.4 hours.
Charging current: I = P / (U × phases). For 1-phase 230 V: 7.4 kW → 32 A; for 3-phase 400 V: 11 kW → 16 A per phase, 22 kW → 32 A per phase.
Regulatory requirements for a home charging station
EVSE installation is regulated by IEC 61851 (conductive charging), IEC 60364-7-722 (supply of electric vehicles), and national rules (UK: BS 7671 Section 722; Germany: VDE 0100-722; US: NEC 625). Requirements:
— a separate line from the board to the charging station with its own breaker;
— RCD type A or B (DC leakage) 30 mA is mandatory;
— cable with flame-retardant insulation, section per design current: 3.7 kW/16 A — 2.5 mm²; 7.4 kW/32 A — 6 mm²; 11 kW/16 A (3-ph) — 5×2.5 mm²; 22 kW/32 A (3-ph) — 5×6 mm²;
— earthing per the national system (TN-C-S in most of Europe);
— in many EU countries, domestic wallboxes above 3.7 kW require notification to the DSO, and smart charging (EN 50491-12) is mandatory in some markets.
Connectors: Type 2 (Mennekes) for AC and CCS Combo 2 for DC in Europe.
Charging speed table
| Charging type | Power | Current | km per hour (18 kWh/100 km) | Typical use |
|---|---|---|---|---|
| 230 V socket (Type F/G) | 1.4–2.3 kW | 6–10 A | 8–12 km/h | Emergency, overnight |
| Wallbox 1-phase | 3.7 kW | 16 A | 18–20 km/h | Home, night |
| Wallbox 1-phase max | 7.4 kW | 32 A | 35–40 km/h | Home, day |
| Wallbox 3-phase | 11 kW | 16 A/phase | 55–60 km/h | Home/office, night |
| Wallbox 3-phase max | 22 kW | 32 A/phase | 110–120 km/h | Office, commercial |
| Fast DC | 50 kW | DC | 250–280 km/h | Highway |
| Ultra-fast DC | 150–350 kW | DC | up to 1000+ km/h | Highway, hubs |
How to use the calculator
- Select the EV model from the list or enter the battery capacity manually.
- Specify the state of charge before and after (20→80% by default — manufacturers' recommendation).
- Select the charging type: socket, 3.7/7.4/11/22 kW Wallbox or fast DC station.
- For a home station, specify the house allocated power — the calculator will check the margin.
- Press «Calculate» — charging time, current, breaker, RCD, cable, cost.
Common mistakes
- Charging 7.4 kW from a socket — a standard socket handles 16 A max; 32 A requires a separate line.
- RCD type AC instead of A — chargers generate pulsed DC leakage current that type AC cannot detect.
- Two-phase load in a three-phase network — phase imbalance.
- Not accounting for charger efficiency — real time is 10–15% more than the «pure» calculation.
- Charging to 100% daily — accelerated battery degradation; optimal 20–80%.
EV charging FAQ
How long does an EV charge from a home socket?
From a regular 2.3 kW socket — 12–20 hours for a 50–80 kWh battery (20→80% charge). Practical only for overnight charging. For daily use, a 7.4–11 kW Wallbox is recommended: 4–6 hours at night.
Which breaker is needed for an 11 kW charging station?
For three-phase 11 kW (400 V): 16 A per phase, breaker C16 (3P), RCD type A 30 mA, cable 5×2.5 mm². For 1-phase 7.4 kW: breaker C32 (1P), RCD type A, cable 3×6 mm².
Can an EV be charged every day?
Yes, that is what EVs are designed for. The optimal mode: keep the charge at 20–80% (100% is acceptable for LFP with periodic calibration), avoid deep discharge below 10%.
What is more expensive — home or fast station charging?
Home charging on a night tariff is 3–5 times cheaper than fast stations. At 15,000 km/year the difference is significant. Fast stations are for long trips.
Do I need permission for a Wallbox in an apartment?
A station up to 3.7 kW with available capacity — notification procedure in most countries. Above 3.7 kW, coordination with the management company and a capacity check are required. In new buildings, charging stations are often included in the project.