Amp hours to watt hours: Formula, Conversion Table and Examples

Wh = Ah x V is the formula to convert amp hours to watt hours. Multiply the battery’s amp hour (Ah) rating by its nominal voltage (V) to get watt hours (Wh).

Ah (amp hours) is the battery’s charge capacity in amperes for one hour. V (volts) is the battery’s nominal voltage. Wh (watt hours) is the total energy stored, in watts delivered for one hour.

How do I convert amp hours to watt hours with real battery values?

To convert 100Ah at 51.2V to Wh: 100 x 51.2 = 5,120Wh. This matches the rating for many 5kWh home batteries.

To convert 200Ah at 51.2V to Wh: 200 x 51.2 = 10,240Wh. This is the capacity for a typical 10kWh stackable battery.

To convert 280Ah at 384V to Wh: 280 x 384 = 107,520Wh. This is the energy for a 100kWh commercial storage cabinet.

What is the most common mistake when converting Ah to Wh?

The most common mistake is using mAh (milliamp hours) as if it were Ah. 1,000mAh = 1Ah. Always divide mAh by 1,000 before using the formula. Another mistake is using peak or minimum voltage instead of nominal voltage. Use the nominal voltage printed on the battery label for accurate sizing.

Why does amp hours to watt hours conversion matter in battery procurement?

Suppliers quote battery capacity in Ah, Wh, or kWh. Comparing batteries requires converting all values to Wh or kWh using the same nominal voltage. This ensures you compare usable stored energy, not just charge capacity.

How do I use this formula for different battery types?

The formula Wh = Ah x V applies to all battery chemistries and voltages. For multi-cell batteries, use the total nominal voltage of the assembled pack, not the cell voltage. For example, a 12V 100Ah LiFePO4 battery: 100 x 12.8 = 1,280Wh.

Check your battery’s specification sheet for nominal voltage and amp hour rating, then run the calculation to confirm usable energy before procurement or system sizing.