Free energy calculator

Watt-Hours to Amp-Hours Converter

Convert stored energy in watt-hours to charge capacity in amp-hours. Voltage is required because Ah alone does not describe energy.

Calculate your estimate

Change the example values to match your system.

Wh

Enter energy in Wh. Supported input range: 0.1 to 1,000,000 Wh.

V

Enter nominal voltage in V. Supported input range: 0.01 to 10,000 V.

Estimated result

Result—

Enter valid inputs and calculate to see results.

These are estimates, not guaranteed performance.

Formula and method

Amp-hours (Ah) = watt-hours (Wh) ÷ nominal voltage (V).

Displayed results are rounded to two decimal places.

What the inputs mean

Energy (Wh)
Enter energy in Wh.
Nominal voltage (V)
Enter nominal voltage in V.

Worked example

1,200 Wh divided by 12 V equals 100 Ah (100,000 mAh).

Why the real result may differ

  • The conversion depends on the nominal or measured voltage entered; voltage that changes during operation changes the corresponding charge value.
  • This direct unit conversion does not apply efficiency, loss, or safety margins. Account for those separately when modeling a real system.

Common mistakes

  • Do not convert Wh to Ah without specifying voltage.
  • Do not assume this unit conversion includes converter losses or a design margin.

Frequently asked questions

Does this conversion include efficiency or losses?

No. It applies only Ah = Wh / V. Include equipment losses separately for a real system estimate.

Related tools

References

Last reviewed: August 12, 2026