Chuck Size
Affiliate link — we may earn a commissionThe chuck is the clamp at the front of the drill that grips the bit. Chuck size tells you the largest bit shank the tool accepts. Most cordless drills use a 1/2-inch keyless chuck, which handles bit shanks from 1/16-inch up to 1/2-inch. Compact drills sometimes use a 3/8-inch chuck, which limits you to smaller bits but saves weight and length. Impact drivers skip the chuck entirely and use a 1/4-inch hex collet that only accepts hex-shanked bits.
Why It Matters
A 1/2-inch chuck handles any standard drill bit you'll buy at a hardware store. A 3/8-inch chuck locks you out of larger spade bits and some hole saws. Know what bits you need before you buy the tool.