Bolt, Screw or Stud?
Three words that get used loosely — here’s the real difference in about a minute, so you ask for the right thing and we hand you the right thing.
People use these names loosely, and at the counter we know what you mean either way. But the real difference comes down to one thing: how the fastener is held and tightened.
Bolt
A headed fastener that passes through the parts and is held by a nut on the other side. The bolt usually stays still while the nut is turned to clamp things together.
Screw
A headed fastener that threads into the material itself — a tapped hole, or threads it cuts as it goes. No nut needed. You turn the screw by its head to drive and tighten it.
Stud
A length of threaded rod with no head — threaded on both ends or all the way along. One end anchors into a part or stays fixed; nuts go on to clamp. Common where you need to slide a part on, then secure it.
So why does “hex cap screw” exist?
Same part, two names. Most people say hex bolt; catalogs and standards say hex cap screw. The name follows how it’s used, not the part itself:
So don’t overthink it. Tell us what you’re doing — “going through with a nut” or “threading into a block” — and we’ll match the right part, whichever word you use.
One thing that does matter: whether you need a nut with it. Tell us if you’re using a nut (and whether you need washers too), and we’ll make sure the threads and grade all match across the set.
The quick test
That one question sorts out almost every case.
Know which one you need? Here’s what’s next.
Once you’ve got the type, the rest is size, thread, grade, and finish. These pick up from here.