Use this electronics calculation for a first-pass component, converter, signal, motor, or sensor estimate when the stated operating conditions and units match the device data.

Remaining capacity (Ah)

Charge currently stored in the battery.

Full capacity (Ah)

Rated full capacity of the battery.

Compute the state of charge of a battery from remaining and full capacity. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

State of charge (%)

Percentage of full capacity still stored.

• Battery capacity, state of charge, runtime, and aging depend on chemistry, temperature, discharge profile, cutoff voltage, cell balance, charge method, rate capability, self-discharge, and prior history. Nominal amp-hour or watt-hour ratings do not guarantee usable energy under every load.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check the result against the current datasheet and worst-case operating corners, then verify the circuit or measurement with simulation and bench testing where failure matters.

• Battery Remaining Capacity

  Calculate remaining battery charge in ampere-hours from measured full-charge capacity and state of charge percentage.

• Battery State Of Health

  Calculate battery state of health as measured full-charge capacity divided by rated new capacity, expressed as a percentage; values over 100% can be valid measurements.

• Battery Cycle Count Estimate

  Estimate full-equivalent battery cycles from total absolute charge-plus-discharge throughput divided by twice the rated ampere-hour capacity.