Are Socket Wrenches Universal? (Explained!)

Socket wrenches (or socket spanners) are universal and interchangeable. It uses a closed socket format, rather than a typical open wrench/spanner to turn a fastener, typically in the form of a nut or bolt. The advantage of interchangeable sockets is using a separate wrench for each of the many different fastener sizes and types, only separate sockets are needed for each size and type.

Nearly all screw and bolt types now have sockets of different types made to fit their bolts or nuts. The wide range of square drive sizes provides for a wide variety of socket types and sizes to suit small to very large nuts and bolts.

Sockets often come as a “socket set” with many different sizes or types of sockets to fit the heads of different-sized fasteners. A ratchet of the “set size” is often included with the socket set. Sockets are commonly available in fractional inch and metric sizes, and in short (shallow) and longer (deep) varieties.

Are all socket wrenches the same?

If the socket size is the same, the socket wrenches are the same. Universal sockets come in different sizes. A socket wrenches have a socket set. Sockets are interchangeable in some specifications.

The most common type of socket wrench. The ratcheting mechanism allows the nut to be tightened or loosened with a reciprocating motion, without requiring that the wrench be removed and refitted after each turn. Typically, a small lever on the ratchet head switches the wrench between tightening and loosening mode.

These drive fittings come in four common socket sizes: 1/4 inch (0.6 centimeters), 3/8 inch (0.9 centimeters), 1/2 inch (1.3 centimeters), and 3/4 inch (1.9 centimeters). In-between sizes are available too, starting with 1/4 inch (0.6 centimeters) and increasing every sixteenth of an inch (0.16 centimeters).

But most commonly there are only two: standard and large. The standard size has an overall diameter of 1″ (25.4mm) and can be used on fastener heads ranging from ¼” – ¾” (7mm-19mm). It also has a ⅜” drive for connecting a turning tool.

A set of deep sockets on a rail.
A set of deep sockets on a rail.

Socket Wrench History

The ratcheting socket wrench, with interchangeable (indexable) sockets, was invented by an American, J.J. Richardson, of Woodstock, Vermont. The tool was patented (U.S. Patent 38,914) through the Scientific American Patent Agency on June 16, 1863. The first illustration of the tool appears on p. 248 of the April 16, 1864 issue of Scientific American. In current American English usage, the term “socket wrench” describes the wrench, not the socket. However, the term “socket wrench” is not used in British English

How Ratchets and Sockets Work

A ratchet is a handle that snaps into one end of a socket by means of a square-drive connector. The other end of the socket fits over a fastener. A mechanism in the ratchet allows the handle to engage and tighten the fastener when you swing it in a clockwise direction and turn freely when you swing it counterclockwise. A switch on the ratchet reverses the action to loosen the fastener.

Ratchets: What You Need to Know

The most prevalent form is the ratcheting socket wrench, often informally called a ratchet. A ratchet incorporates a reversible ratcheting mechanism that allows the user to pivot the tool back and forth to turn its socket instead of removing and repositioning a wrench to do so.

ratcheting socket wrench

Whether you’re working on a car, a piece of machinery, or taking on a building project, a ratchet is an essential tool. Commonly used for fastening nuts and bolts, there are different types of ratchets available. Here are some important things to note:

  • Ratchet sizes differ according to usage. Common ratchet sizes include 1/4-in. drive, 3/8-in. drive, 1/2-in. drive and 3/4-in. drive. Having different socket wrench sizes will allow you to operate different socket sizes based on your particular needs.
  • Most ratchets use a geared drive. Gearless options use a rolling bearing, which can help you make greater changes with less effort. Jointed and flex-head ratchets are helpful for working in small, hard-to-reach areas.
  • Tooth count of ratchets can vary. The teeth — the number of notches in the gear inside the ratchet head — are a factor when it comes to usage. A higher tooth count, from about 72 to 160 teeth, requires less handle movement to turn a fastener. This allows the user to work in small confined spaces. A lower tooth count requires greater handle movement for a turn. 

Types of Sockets

Sockets connect to the ratchet to help you make adjustments quickly and easily. Depending on the job at hand, you’ll need a certain type of socket. Here’s a breakdown of the most common socket types you’ll find and when you’ll likely use them:

  • SAE sockets: Society of Automotive Engineers (SAE) sockets are manufactured for work on American-made vehicles. Socket sizes are measured based on imperial system inches and fractions. Some of the commonly used SAE sizes are 3/8 in., 5/8 in., and 11/16 in. sockets.
  • Metric sockets: Ideal for working on imported vehicles, metric sockets’ sizes are measured in millimeters. The most commonly used types are 8 mm, 10 mm and 14 mm sockets.
  • Torx® bit sockets: The sockets are fitted with star-shaped bits designed for Torx® screws. Torx bit socket sizes are identified with the capital “T” followed by a number. The socket sizes range from T1 to T100, with the most common for Torx screws T6, T8, T10, T15, T20, T25, and T30. Torx screw sockets are ideal for where you need extra power and more torque. 
  • Impact sockets: Designed to be used with impact wrenches, impact sockets are ideal for heavy-duty tasks such as removing old, difficult, or rusted bolts on cars or machinery. SAE and metric impact socket sizes are both available. 
  • Driver sockets: Also called bit sockets, these work to tighten and loosen screws using your ratchet handle. Driver sockets are available for almost all screw types like Phillips, flat head, and hex. 
  • Pass-through sockets: These allow the bolt you’re working on to pass through the socket and ratchet. This function can be useful for long, threaded bolts in cars, electronics, and machinery. 
  • Spark plug sockets: Specially fitted for changing spark plugs, spark plug sockets make quick work of this automotive repair job.
socket set
A typical professional-grade socket set in a metal box

Ratchets and sockets come in many sizes, types, and uses for varying tasks. When you buy specialty ratchet and socket sets, they may include items like socket extensions and breaker bars. However, you can add these items to your existing sets, as they’re typically sold individually. In case you lose or damage a part of your existing set, you can buy replacement sockets and more.

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