The simple answer is SAE wrenches are more common in the USA than metric wrenches, but the situation is more nuanced than that. The prevalence of one over the other depends heavily on the context.
While the United States predominantly uses the SAE (inches) system for many everyday applications, the increasing globalization of manufacturing and the widespread adoption of the metric system worldwide have led to a blend of both systems in American mechanics and automotive repair.
What is SAE and Metric?
Before diving into the comparison, let's clarify the terminology.
-
SAE (Society of Automotive Engineers): This system uses inches and fractions of inches for measurements. It's the traditional system used in the US for many applications, particularly older vehicles and machinery. Common SAE wrench sizes include 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", etc.
-
Metric: This system uses millimeters (mm) for measurements. It's the globally dominant system, and newer vehicles and equipment are increasingly using metric fasteners. Common metric wrench sizes include 6mm, 8mm, 10mm, 12mm, 13mm, 14mm, etc.
Where You'll Find Each More Commonly
-
Older Vehicles and Machinery: You'll overwhelmingly find SAE wrenches used to service older American cars, trucks, and various pieces of machinery. Many older homes and appliances also utilize SAE-sized bolts and nuts.
-
Newer Vehicles and Machinery: Newer vehicles, particularly those manufactured by foreign companies, predominantly use metric fasteners. Many modern tools and equipment also employ metric measurements.
-
Bicycle Repair: The bicycle industry has largely adopted the metric system, so metric wrenches are essential for bike maintenance.
Why the Prevalence of SAE in the USA?
The SAE system's continued presence in the US is a result of its historical dominance and inertia. Changing over to a completely metric system would be a massive undertaking, requiring significant investment and retraining across various industries.
Do I Need Both SAE and Metric Wrenches?
The short answer is yes, especially if you work on a variety of vehicles and equipment. A comprehensive wrench set typically includes both SAE and metric sizes. Having both allows you to tackle almost any repair job you might encounter.
What Wrench Sizes Should I Buy First?
If you're starting a wrench collection, prioritize the sizes you'll use most often. This will vary based on your specific needs. Consider the types of vehicles or equipment you work on most frequently to determine which system (SAE or Metric) you need to prioritize initially. A basic set encompassing both systems is a good starting point for most DIY enthusiasts.
Are there hybrid wrenches?
Yes! Combination wrenches, which have both an open-end and a box-end, are often available in both SAE and metric sizes. These are a versatile and practical choice for most applications.
Conclusion: It's a Mix
While SAE wrenches are more common in the USA than metric wrenches, particularly in older applications, the metric system's global dominance means both are necessary for a complete toolkit. The best approach is to own both SAE and metric wrenches, especially as modern applications increasingly favor the metric system.
