What is the Difference Between Grade 5 and A325?

The grading system for American steel differs significantly.

Steel in America has different grading systems. Knowing the difference between Grade 5 and A325 can keep you from purchasing the wrong items for your next project. To help you understand what makes the two entirely different products, we’re explaining the qualities and uses of Grade 5 bolts and A325 bolts.

Grade 5

The Society of Automotive Engineers (SAE) classification system specifies what is Grade 5 steel. It’s among the biggest differences between Grade 5 and A325 bolts. This type of bolt is popular and readily available. OEM applications often call for Grade 5 fasteners.

Grade 5 bolts range from ¼” to 1 and ½” in diameter. A different classification is necessary for bolts larger than 1 and ½”. When completed, a manufacture Grade 5 bolt is a finished hex bolt with nuts that also feature a pattern that is finished hex.


The ASTM specifies which bolts fall under the A325 classification. The head-on the bolts is heavier. The nuts that fit them must be heavy-duty and made for use with A325 bolts. The tread lengths differ, too. A325 bolts are shorter in most cases than other types of graded bolts. Grade 5 fasteners adhere to standard dimensions during the manufacturing process.

They are twice the diameter with an extra 1/4” for bolts 6” inches or less. They are also twice the diameter for 6” and longer bolts with an added ½.” Projects that require a longer length of fastener find that Grade 5 bolts are best.

Order the Right Grade of Bolt from Fasteners Direct Today

Now that you know the difference between Grade 5 and A325, you’ll have an easier time shopping Fasteners Direct’s online catalog. You’ll get exactly what you need to complete your product. As always, you’re welcome to contact us with any questions or concerns you might have about the ordering process.

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