Drive Size
Affiliate link — we may earn a commissionDrive size is the square nub on the wrench or ratchet where the socket attaches. Common sizes are 1/4-inch, 3/8-inch, and 1/2-inch. The size determines what socket sets and extensions fit the tool. 1/4-inch handles small bolts and tight spaces (think electrical panels and small engine work). 3/8-inch covers most automotive and mechanical work. 1/2-inch is for lug nuts, suspension work, and heavy structural bolts. A 3/8-inch cordless ratchet with a 1/2-inch adapter adds versatility but reduces the rated torque capacity.
Why It Matters
Your drive size has to match your socket set. If you already own 3/8-inch sockets, get a 3/8-inch ratchet. Adapters work but they add length and reduce torque transfer. For most people, 3/8-inch covers the widest range of jobs.