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E-Mobility Tool

EV Charging Calculator

Calculate EV charging time, energy and cost for a single vehicle on a wallbox, or size grid-connection capacity for a multi-point commercial charging site.

Updated: July 4, 2026Planning reference

Quick Answer

Charging time depends on the smaller of the wallbox and the car's onboard charger, not just the wallbox rating.

Consumer mode estimates time, energy and cost for one vehicle. Commercial mode sizes the required grid-connection capacity for a multi-point charging site using a simultaneity factor.

Consumer

Charging input

Enter battery, state of charge and charger details. Time, energy and cost update automatically.

Formula used

Time ≈ energy into battery ÷ (effective power × efficiency). Effective AC power is limited by the smaller of the wallbox and the car's onboard charger.

Commercial

Site sizing input

Enter the charge-point count, power per point and simultaneity factor for the site.

Simultaneity factor guidance

Few charge points (1–2) → close to 1.0 (all can charge at once). Many points (10+) → typically 0.3–0.5, since not every vehicle charges at full power simultaneously.

Formula used

Required kW ≈ (points × power per point) × simultaneity factor. Current assumes 400 V three-phase, power factor ≈ 1.

Formula / Method

How the calculator works

Consumer mode converts the state-of-charge gap into an energy requirement, divides by the effective charging power (the smaller of the wallbox and the car's onboard AC charger) and the charging efficiency to get time, then applies the efficiency loss again to get energy drawn from the wall and its cost. Commercial mode multiplies charge-point count by power per point, then applies a simultaneity factor to estimate the required grid-connection capacity.

Time ≈ energy ÷ (effective power × efficiency)

Inputs

Required inputs

Consumer: battery capacity, start/target state of charge, charger power and type, vehicle onboard AC charge rate, efficiency and electricity price. Commercial: charge-point count, power per point and simultaneity factor.

Uses

Where this helps

Useful for estimating home or destination charging time and cost, checking whether a wallbox needs grid-operator notification or approval, and early planning of multi-point commercial or workplace charging site grid-connection capacity.

FAQ

EV charging notes

Why doesn't a 22 kW wallbox always charge faster?

AC charging speed is limited by the smaller of the wallbox and the car's onboard AC charger — most consumer EVs have an 11 kW onboard charger, so a 22 kW wallbox charges no faster than 11 kW unless the car itself supports higher onboard AC charging.

11 kW vs 22 kW — what must I tell the grid operator?

In Germany, wallboxes up to 11 kW are anmeldepflichtig (must be registered with the network operator before or shortly after installation). Wallboxes above 11 kW up to 22 kW are genehmigungspflichtig (require the network operator's approval before installation), per §19 NAV and VDE-AR-N 4100.

Consumer vs commercial mode?

Consumer mode estimates charging time and cost for a single vehicle. Commercial mode sizes the required grid-connection capacity for a multi-point charging site, applying a simultaneity factor since not every charge point draws full power at the same time.

Learn More

Reference links

Project

Need help planning EV charging infrastructure?

ITCOREOPS can support wallbox and commercial charging site planning, grid-connection coordination and load-management design.

Open project formVisit ITCOREOPS →

Disclaimer

Planning reference only

Planning estimate. Real charging follows a taper curve (the BMS reduces power above ~80% SoC, so DC fast-charge times are longer than linear), and depends on temperature, vehicle and cable. Grid-connection registration/approval and load management must be confirmed with the network operator (Netzbetreiber); the installation itself requires a qualified electrician.

Workflow

Check charging time, cost and grid-connection requirements before installing a wallbox or charging site.

Use this calculator before ordering a wallbox, notifying the grid operator, or sizing a commercial charging site's grid connection.

Use exact inputs ↑

Support

Need help with EV charging or electrical planning?

For wallbox planning, commercial charging sites, load management and electrical infrastructure support, visit ITCOREOPS.

Visit ITCOREOPS →Email ITCOREOPS ✉

Feedback

Found a bug or calculation issue?

Report display problems, calculation issues or suggestions for improving this calculator.

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Worked example

Inputs: 75 kWh battery, 20% → 80% state of charge, 11 kW AC wallbox, car onboard charger 11 kW, 88% efficiency, €0.35/kWh.

Result: 45 kWh into the battery → ≈ 4 h 39 min charging time; ≈ 51.1 kWh drawn from the wall → ≈ €17.90. Note: an 11 kW wallbox is notify-only (anmeldepflichtig) — no approval required.