Formula and meaning
Battery capacity, start and target state of charge, charging power, and efficiency define an idealized average charging time.
E₍battery₎ = C · (SOC₂ − SOC₁) / 100 · E₍grid₎ = E₍battery₎ / η · t = E₍grid₎ / P
E-mobility · charging infrastructure
EV Charging Time Calculator
Calculate EV charging time, grid energy and charging losses between two battery states of charge.
EVAC/DC
02
Results
E = P · t
Set the inputs and run the calculation.
Context
82 kWh from 20% to 80% at 11 kW and 90% efficiency gives 49.2 kWh in the battery, 54.667 kWh from the grid, and about 4 h 58 min.
Charging power is treated as constant. DC fast charging is affected by the charging curve, temperature, vehicle, charger, and battery management; the estimate is generally closer for AC charging. No vehicle-specific charging curve or automatic infrastructure selection is included.
Inputs and method
EV charging time explained
Estimate battery energy, grid energy and time between two states of charge.
Inputs
Usable battery capacity, start and target SOC, charging power and total efficiency define the balance.
SOC difference applies to usable capacity; P is electrical input power and is not necessarily battery power. Efficiency explains why grid and stored energy differ.
Calculation
Battery energy = capacity·SOC difference; grid energy = battery energy/η; time = grid energy/charging power.
Example
82 kWh from 20 to 80% at 11 kW and 90% gives about 4 h 58 min.
Sources and limits: Energy balance. DC charging curves, temperature and battery management reduce accuracy.
EV charging time explained in detail
Estimate battery energy, grid energy and time between two states of charge.
What does this quantity describe?
Energy calculators balance quantities over time and separate useful energy, losses and grid import. This matters because power is instantaneous while energy is its time integral.
Formula and variables
Battery energy = capacity·SOC difference; grid energy = battery energy/η; time = grid energy/charging power.
Choose the inputs correctly
Usable battery capacity, start and target SOC, charging power and total efficiency define the balance. SOC difference applies to usable capacity; P is electrical input power and is not necessarily battery power. Efficiency explains why grid and stored energy differ.
How to use the calculator
Enter usable battery capacity, start and target state of charge, the actual charging power reaching the vehicle (not the wallbox's rated power) and overall efficiency. The calculator derives battery energy, grid energy and the resulting charging time.
Worked example
82 kWh from 20 to 80% at 11 kW and 90% gives about 4 h 58 min.
Understand the result and units
SOC difference applies to usable capacity; P is electrical input power and is not necessarily battery power. Efficiency explains why grid and stored energy differ. An annual value describes a scenario, not a guarantee for every day. Efficiency, coincidence, temperature, driving profile and tariff assumptions can change practical results more than rounding.
Capacity and energy in kWh, charging power in kW, SOC and efficiency in percent, charging time in hours and minutes.
Typical applications
Estimating charging duration for trip planning, comparing different charging powers, or checking whether a session can realistically finish overnight or during a break.
Assumptions, limits and common mistakes
Energy balance. DC charging curves, temperature and battery management reduce accuracy.
Common mistake: Don't enter the wallbox's rated power instead of the power actually reaching the vehicle – cabling, the onboard charger and battery temperature can hold real power well below the rating. For DC fast charging, also note the charging curve tapers above about 80% SOC, which this constant-power model does not capture.
Frequently asked questions
Why does real charging time differ from the calculation?
The model assumes constant charging power. Real charging curves taper above about 80% SOC, and cold weather, battery management or a weaker wallbox can further limit actual power.
Which charging power should I enter?
The smallest power in the chain of vehicle, cable and charging point – often either the vehicle's onboard charger or the wallbox/station limits the actual power.
What does overall efficiency mean here?
It combines AC/DC conversion in the onboard charger and battery charging losses, explaining why grid energy is always higher than the energy stored in the battery.
Dynamic tariff? Find the cheapest charging window with the electricity charging planner →