Key Facts
- A 5-cell lithium-ion pack is 18 V nominal and reads about 20 V with no load, fresh off the charger.
- DeWalt 20V MAX, Craftsman V20, Milwaukee M18, Makita 18V LXT, Ryobi ONE+ and Bosch 18V are all the same voltage class.
- 1 foot-pound = 12 inch-pounds. A 400 ft-lb impact wrench is 4,800 in-lbs.
- Amp-hours measure capacity, not power. A 2.0Ah and an 8.0Ah pack from the same platform deliver the same voltage and near-identical peak torque.
- 18650 and 21700 are cell sizes (18x65 mm and 21x70 mm), not brands or performance tiers.
- Brushless motors typically give 20-50% more runtime per charge than an equivalent brushed motor, at a real price premium.
- Hammer drills and SDS rotary hammers use incompatible bit systems.
- Impact drivers use 1/4-inch hex; impact wrenches use a square drive. Not interchangeable without an adapter.
Full sourcing: the Voltage Reality Index and the Torque Unit Decoder.