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Amp Hours To Watt Hours Calculator

Work out amp hours to watt hours instantly with clear inputs, formula shown and shareable results.

About Amp Hours To Watt Hours Calculator

Watt-hours equal amp-hours times voltage, which is why amp-hours alone cannot be compared across different battery voltages. A 100 Ah 12 V battery holds 1.28 kWh; a 100 Ah 48 V battery holds four times that.

Formula

Energy conversion

Wh = Ah x V; usable Wh = Wh x depth of discharge

Worked example

With the default values below, Amp Hours To Watt Hours Calculator returns Energy of 1,280.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Capacity
100 Ah
Nominal voltage
12.8 V
Usable depth of discharge
90 %

Results

Energy
1,280.00 Wh
Usable energy
1,152.00 Wh
Energy
1.2800 kWh
Equivalent capacity at 230 V
5.5652 Ah

Step by step

  1. 1Values used
  2. 2Energy conversion
  3. 3Energy= 1,280.00 Wh
  4. 4Usable energy= 1,152.00 Wh
  5. 5Energy= 1.2800 kWh
  6. 6Equivalent capacity at 230 V= 5.5652 Ah

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.

Frequently Asked Questions

Why do vendors quote amp-hours?

Historical convention from lead-acid systems at a fixed 12 V. It is meaningless for comparison unless the voltage is stated too.

Which voltage should I use?

Nominal voltage for energy content — 12.8 V for a 4S LFP pack, 3.7 V per lithium-ion cell — not the fully charged voltage.

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