Power converter

Amp-hours to Watts Calculator

Convert battery capacity in amp-hours into the power in watts it can sustain.

How Ah to Watts works

A battery's amp-hour rating combined with its voltage gives its total energy in watt-hours. Divide that energy by the discharge time to find the average power in watts it can sustain.

This is the reverse of the watts-to-amp-hours calculation. It answers a practical question: given a battery of a certain capacity and voltage, what continuous load in watts can it support for a set number of hours?

Formula

1W = (Ah × V) ÷ h

Watt-hours = amp-hours × volts; watts = watt-hours ÷ hours.

Ah to Watts conversion table

Reference Table5 rows

Sustained watts from a 12 V battery over 5 hours.
Capacity↕	Energy (Wh)↕	Over 5 h↕	Over 10 h↕
20 Ah	240 Wh	48 W	24 W
50 Ah	600 Wh	120 W	60 W
100 Ah	1,200 Wh	240 W	120 W
200 Ah	2,400 Wh	480 W	240 W
300 Ah	3,600 Wh	720 W	360 W

💡 Click any row to auto-fill the calculator aboveClick column headers to sort

FAQ: Ah to Watts

How do you convert amp-hours to watts?

Multiply amp-hours by voltage to get watt-hours, then divide by the discharge time in hours. W = (Ah × V) ÷ h. For example, 100 Ah at 12 V over 5 h = 1,200 Wh ÷ 5 = 240 W.

How many watts is a 100Ah 12V battery?

A 100 Ah 12 V battery stores about 1,200 watt-hours. It can supply 240 W for 5 hours, 120 W for 10 hours, or 1,200 W for 1 hour, before accounting for depth-of-discharge limits.

Does discharge time change the wattage?

Yes. The stored energy is fixed, so a shorter discharge time means a higher sustainable wattage and a longer time means lower wattage.

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