About the Battery Charging Time Calculator
How long a battery takes to charge from its capacity, charger current and state of charge.
Also known as: charge time calculator, how long to charge battery, battery-charging-time, ev charge time battery.
How to use this calculator
- Enter battery capacity, charger current, current state of charge, target state of charge and the other fields.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
time = Ah to add ÷ charger current ÷ efficiency
Worked example
Using the values pre-filled in the calculator above:
- Battery capacity = 100 Ah
- Charger current = 20 A
- Current state of charge = 20 %
- Target state of charge = 100 %
- Charging efficiency = 90 %
the calculator returns:
- Charging time: 4 h 27 min
- Decimal hours: 4.444
- Charge to add: 80 Ah
- C-rate of this charge: 0.2 C