Battery Charge Time Calculator
Estimate how long a battery will take to charge from its capacity and the charger's current.
Charge time from capacity and current
Roughly, a battery's charge time is its capacity divided by the charging current — a bigger battery or a weaker charger takes longer. This estimates it from those figures, so you can tell whether a device will be ready in an hour or need to sit overnight.
Enter the battery capacity and charging current to see the estimate.
Why real charging isn't linear
The simple division gives a ballpark, but real charging is slower than it suggests for a good reason. Batteries charge quickly up to around 80% and then deliberately slow down to protect their health and avoid overheating, which is why the last stretch to full takes disproportionately long — and why fast-charge claims usually quote the time to 80%, not 100%. Charging is also less than perfectly efficient, losing a little as heat, so treat the figure as a floor.
Battery Charge Time Calculator FAQ
Why does the last bit of charging take so long?
Batteries slow their charging after around 80% to protect their health and avoid heat, so the final stretch to full is disproportionately slow.
Will the real charge time match the estimate?
It is a floor — real charging is a little slower due to the tapering near full and some energy lost as heat.
Is anything uploaded?
No. The calculation happens in your browser.