What is fret buzz and how do I fix it?

Fret buzz is a rattling or buzzing sound that happens when a vibrating string makes contact with a fret (or frets) it isn't supposed to touch during its normal vibration arc. It's one of the most common complaints in guitar repair, and also one of the most commonly misdiagnosed, because "buzz" can point to several completely different underlying causes.

The main causes, and how to tell them apart

• Low action. Causes buzz fairly evenly across the whole neck, and generally improves as you raise the action.
• Insufficient neck relief. Causes buzz concentrated in the middle of the fretboard, since a too-flat or back-bowed neck removes clearance exactly where a vibrating string needs it most.
• Uneven or high frets. Causes buzz at specific, isolated locations, no matter how much you raise the overall action, because the problem is one fret being taller (or its neighbors being lower) rather than a general clearance issue.
• Nut slot cut too low. Causes buzz specifically on open strings that clears up once you fret past the first couple of frets.
• Loose hardware. Occasionally the buzz isn't the string against a fret at all — it's a loose tuner, bridge component, or truss rod cover rattling sympathetically.

Why "just raise the action" isn't always the right fix

Raising action solves buzz caused by low action, but it doesn't fix relief, fret unevenness, or nut issues — it just adds clearance everywhere, including on the parts of the guitar that didn't need it, which makes the guitar harder to play than necessary to solve a localized problem.

How to actually diagnose it

Notice where the buzz happens: open strings only, a specific fret area, or everywhere evenly. That alone points you toward the right category of cause before you touch a single adjustment screw.

The bottom line

Buzz has a specific cause, and finding that cause is most of the battle. Randomly adjusting truss rod, then saddle, then nut, hoping something sticks, usually just introduces new problems on top of the original one. If you can't pin down the pattern yourself, that's exactly the kind of thing worth a proper diagnostic look.