The names do not give a complete specification
A bolt commonly works with a nut, but fastener names overlap. A machine screw can also fit a nut or a tapped hole, while a lag bolt has a pointed wood thread. Use the name as a starting category rather than as the only basis for a replacement.
Identify what the fastener goes into
Look at the original assembly: does it pass through parts into a nut, enter an existing threaded hole, or fasten into wood or sheet metal? This helps distinguish fastener families. Keep any washers or other parts with the sample so the complete arrangement can be identified.
Match more than the head shape
Compare diameter, thread specification, length, head and drive type. Check the required material, coating and strength specification from the original product or instructions. A similar-looking hex head or a nut that starts turning does not establish a correct match.
Describe the job when asking for help
Bring the sample and explain the material and equipment it came from. Ask staff to help identify its specification and find the corresponding product. If the original fastener is damaged or missing, use the equipment documentation; do not rely on the choice between the words screw and bolt.
Find a nearby location in our hardware stores directory, or continue with types of drill bits: match the material and the tool.
Published 2026-11-03 · reviewed with each rebuild, last November 2026.
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