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Instant result
Enter the data and press the button to do the calculation.
Online Calculator
Battery charging time calculator
Enter capacity, current charge percentage, target charge, and charging current to estimate the time needed.
Idealized estimate. Actual current may decrease during the final charging stages.
Information
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Local processing
The values are processed directly in your browser.
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Free
No registration, external API or subscription required.
Frequently asked questions
What is the basic formula?
Time ≈ Ah to replenish / effective charging current.
Why is efficiency included?
To provide a simple estimate of losses during charging.
Does the current remain constant?
Not always. Many chargers reduce the current during the final charging stages.
Is that an exact estimate?
No. It is a useful approximation, not a complete model of battery chemistry.