Bolt vs Screw: What's the Difference?
When to use a bolt or a screw, and how to size them with metric and imperial tools.
Bolt vs screw definition
A bolt usually goes through unthreaded holes in both parts and is secured with a nut. A screw typically threads into a pre-tapped hole or the material itself (e.g. wood, sheet metal). In practice the terms overlap—machine screws can take nuts, and some “bolts” thread into tapped holes. For sizing, use the same screw converter and thread identifier for both.
Comparison: bolt vs screw
| Bolt | Screw |
|---|---|
| Used with a nut | Often threads into material or tapped hole |
| Through-hole, no internal thread | Requires pilot/tapped hole or soft material |
| Higher clamp load, reusable | Wide range of head/drive types |
| Hex head common | Phillips, Torx, hex, etc. |
When to use which
Use bolts for structural joints, when you need a nut, or when you disassemble often. Use screws when you're threading into a tapped hole, wood, or sheet metal, or when head style and drive matter more. Thread pitch and diameter still follow the same standards—check our screw size chart and tap drill chart for equivalents.
FAQ
What is the difference between a bolt and a screw?
Bolts typically use a nut and pass through unthreaded holes; screws often thread into a tapped hole or the material. Bolts are common for high clamp load and reuse.
When should I use a bolt instead of a screw?
When you need a nut, high clamp load, or frequent disassembly. Use screws for tapping into material or when head/drive type is important.
Do bolts and screws use the same thread pitch?
Yes. Metric and UNC/UNF apply to both. Use our thread identifier or screw converter to match size and pitch.