Buying a Socket Set: Drive Sizes, 6 vs 12 Point, and What to Skip

A socket set is the tool you will own longest, and the 200-piece kit on the end cap is usually the wrong way to start.

Drive sizes, and what each is for

The drive size is the square hole the ratchet plugs into.

Drive	Socket range	Use
1/4”	4–14 mm	Interior trim, electronics, small engines
3/8”	8–19 mm	The workhorse. Most engine bay work
1/2”	10–32 mm	Suspension, wheels, crank bolts
3/4”+	Larger	Truck and industrial only

If you buy one set, buy 3/8-inch. It reaches into tighter spaces than 1/2 and takes far more torque than 1/4. Add 1/2-inch when you start doing suspension or wheels — wheel nuts at 100 ft-lb are past what a 3/8 ratchet should see.

6-point vs 12-point

This is the choice that actually matters.

A 12-point socket engages a hex fastener in twelve positions, so it goes on at 30-degree increments instead of 60. Convenient in tight spaces.

A 6-point socket contacts the flats of the fastener rather than the corners. On anything rusted, painted, or previously abused, that is the difference between loosening a bolt and rounding it off.

Buy 6-point for automotive and anything outdoors. Keep 12-point for low-torque work in awkward positions. If a kit offers only 12-point, that tells you what kind of kit it is.

Deep vs shallow

You want both, and most kits shortchange the deep sockets. Deep sockets reach studs and recessed bolts; shallow sockets fit where a deep one bottoms out on an obstruction. A set with 20 shallow and 6 deep is unbalanced — check the split before buying.

What the big kits get wrong

A 230-piece set typically pads its count with:

Screwdriver bits you already have, in a holder that fits nothing well.
Both metric and SAE in every size, when you probably only need one system. Anything built after roughly 1980 outside the US is metric throughout.
12-point sockets only, because they are cheaper to make.
Sizes nobody uses — 4.5 mm, 23 mm — to inflate the number.
A weak ratchet, which is the part that determines whether you enjoy using the set. Tooth count matters: 72 or 90 teeth gives a 5° or 4° swing arc, versus a coarse 24-tooth ratchet needing 15° to catch.

A well-chosen 60-piece set beats a padded 230-piece one comfortably.

What to prioritise instead

A good ratchet. High tooth count, comfortable handle, smooth mechanism.
6-point sockets in the sizes you actually meet: 8, 10, 12, 13, 14, 15, 17, 18, 19 mm cover most of a car.
Extensions — 3”, 6”, and 10” — plus a wobble extension, which earns its keep the first time a bolt is behind something.
A breaker bar in 1/2-inch. Long, no mechanism to break, and it keeps you from using a ratchet as a lever.
A universal joint and a 1/2-to-3/8 adapter pair.

Chrome vs impact sockets

Chrome sockets are hardened and brittle by design, so they resist wear. Do not use them on an impact wrench — they can shatter. Impact sockets are made of a softer, tougher steel with thicker walls, finished black. If you own an impact wrench, you need impact sockets to go with it.

On lifetime warranties

Several brands warranty hand tools for life, and it is a real consideration for ratchets and sockets, which do eventually fail. Check whether the warranty means walking into a store or posting the tool somewhere and waiting — the difference is most of the value.

Wall thickness and access

Two sockets of the same size are not interchangeable in tight spaces.

Thin-wall sockets fit into recesses and around raised bosses where a standard socket bottoms out. They are also weaker, so keep them for access rather than torque.

Impact sockets have thick walls precisely because they take hammer blows, and that thickness sometimes prevents them fitting where a chrome socket would.

If a socket will not seat fully on a fastener, stop. A socket engaged on half the flat depth will round the fastener at torque, and a rounded bolt is a much longer afternoon than finding the right socket.

Specialist sockets worth owning

Beyond hex, a few show up often enough to be worth having:

Spark plug sockets — deep, with a rubber insert to grip the plug and protect the ceramic. 5/8” and 13/16” cover most petrol engines.
Torx and hex (Allen) bits on a socket drive. European cars use Torx extensively, and the external Torx (E-socket) sizes catch people out.
Wheel nut sockets with a plastic sleeve, so you do not mark alloy wheels.
Oxygen sensor sockets — slotted so the wire passes through.
Oil filter cap wrenches in the size for your engine, for cartridge filters.

Do not buy a “master” set of these speculatively. Buy the size when a job needs it; you will end up with the ones your cars actually use.

Extensions, adapters, and the torque problem

Every joint in the chain between ratchet and fastener adds flex and a place to lose engagement.

Wobble extensions allow a few degrees of misalignment and are genuinely useful, but they reduce the torque you can safely apply.
Universal joints are worse in that respect and should be kept for low-torque access.
Step-up adapters (running a 1/2” socket from a 3/8” ratchet) let you exceed what the smaller ratchet is rated for. It is the ratchet that breaks, usually at an inconvenient moment.
A torque wrench through a universal joint does not give a reliable reading.

For anything with a specified torque, get as short and direct a chain as the access allows.

Storage that keeps a set usable

A socket set’s value collapses the moment you cannot find the 13 mm.

Blow-moulded cases are what sets ship in, and they break and do not lie flat. Two better options: a socket rail per drive size, labelled, in a drawer; or foam organisers cut for the sockets you actually own. Either makes a missing socket visible immediately, which is the whole point.

Keep metric and imperial separated physically. A 13 mm and a 1/2 inch differ by 0.3 mm — enough to round a fastener, not enough to notice by eye.

Care

Chrome sockets need almost nothing: wipe oil off, do not leave them wet. Impact sockets rust, so a light oil film is worth it.

The ratchet is the part with a service life. Most quality ratchets have a rebuild kit — a pawl, spring, and gears — that costs a fraction of the tool. A ratchet that has started to slip under load is a rebuild, not a replacement, and a slipping ratchet is how knuckles meet engine blocks.