Amp-Hours (Ah)

Amp-hours measure a battery's capacity, or how much energy it can store. A 2.0Ah battery can deliver 2 amps for one hour, or 4 amps for 30 minutes, or 1 amp for two hours. In practice, a 5.0Ah battery doesn't last exactly 2.5 times longer than a 2.0Ah battery on the same tool because higher-drain tasks are less efficient. But the ratio is close enough for planning. Most cordless tool platforms offer batteries from 1.5Ah (compact, light) to 8.0Ah or higher (heavy, long runtime). Compact batteries use fewer cells and weigh less. High-capacity packs stack more cells and add weight.