Pick up any guitar. Look at the neck. You’ll see those thin metal strips running across the wood like miniature railroad tracks. Those are frets. What is a fret on a guitar? At its most basic, it’s a divider. It’s a physical boundary that tells the string exactly where to stop vibrating. Without them, you’d be playing a violin or a cello, sliding your fingers around in a desperate, often pitch-deaf search for the right note.
Frets make the guitar approachable. They "quantize" music. They turn a chaotic length of vibrating wire into a series of predictable, mathematical steps called semitones.
If you press your string down behind a fret, you’re shortening the "playing length" of that string. Short string? High pitch. Long string? Low pitch. It’s simple physics, but the way these little metal bars are manufactured, leveled, and polished is actually a high-stakes engineering game that determines whether your $3,000 Gibson feels like a dream or a piece of junk.
How these metal strips actually work
You don't actually press your finger on the metal. If you do, the note sounds dead, thuddy, and muted. You press just behind it.
When you push the string down, the fret acts as a temporary "nut" or bridge. The string vibrates from the bridge of the body up to that specific metal wire. Because the fret is hard—usually made of nickel-silver or stainless steel—it provides a crisp, solid anchor point. This is why guitars have that distinct "ping" and sustain.
The math behind the spacing
Ever noticed how the frets get closer together as you move toward the body of the guitar? That isn't a stylistic choice. It’s the Rule of 18 (specifically $17.817$). To raise a note by a semitone, you have to shorten the string by a specific percentage of its remaining length.
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Because the string gets shorter with every fret you "climb," the distance needed to hit the next semitone also shrinks. If the frets were spaced evenly, the guitar would be impossibly out of tune by the time you reached the third or fourth note. Luthiers used to calculate this by hand with compasses and rulers. Today, CNC machines cut those slots to within a thousandth of an inch. Even a tiny mistake in placement—we’re talking the width of a human hair—can make a guitar impossible to intonate.
What are they actually made of?
Most people call them "nickel-silver" frets. Ironically, there is zero silver in them. None. It’s a blend of copper, nickel, and zinc. It’s soft enough for a tech to file down but hard enough to withstand years of steel strings grinding against them.
Then there’s stainless steel.
Stainless steel frets are the "luxury" option. They are incredibly hard. You can play for twenty years and never see a dent or a flat spot. They feel "slick," making string bends feel like you're sliding on ice. But there's a trade-off. Some purists, like the legendary Eric Johnson, claim they sound "pingy" or too bright. Also, guitar techs hate them because they chew through tools. If you want stainless frets, expect to pay a "toughness tax" at the repair shop.
Why size actually matters
Fret wire comes in different heights and widths. It's not one-size-fits-all.
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- Jumbo Frets: These are tall and wide. You'll find them on Ibanez "shredder" guitars. Because the fret is so tall, your finger barely touches the wood of the fretboard. This makes it effortless to grab the string and bend it way up.
- Vintage Frets: Think 1950s Telecasters. These are tiny. Small. Short. Some people love them because they feel "fast" for chords, but bending a string on vintage frets feels like trying to climb a wall with no handholds. Your finger drags on the wood, creating friction.
- Medium Jumbo: The Goldilocks zone. Most modern Fenders and Gibsons use these. They offer enough height to bend comfortably but don't feel like you're playing on top of speed bumps.
The "Fret Sprout" nightmare
If you’ve ever picked up a guitar and felt like the edges of the neck were trying to saw your hand off, you’ve experienced fret sprout.
Wood is organic. It breathes. When the humidity drops—usually in winter when the heater kicks on—the wood of the guitar neck shrinks. But metal? Metal doesn't shrink. The wood pulls back, leaving the sharp ends of the frets sticking out past the edge of the fingerboard. It’s a sign that the guitar hasn't been humidified properly. It’s fixable, but it’s a jarring reminder that a guitar is a constant battle between biology and metallurgy.
Fretless guitars: The outlier
Yes, they exist. Some jazz and fusion players use fretless guitars to get a "mwah" sound similar to an upright bass. You can slide between notes with total fluidity.
But be warned: it is brutally difficult.
Without the fret to "save" you, if your finger is off by a millimeter, you are out of tune. The fret is your safety net. It’s the grid that keeps the music structured.
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Maintenance and the "Level, Crown, and Polish"
Frets wear out. It’s inevitable. Every time you press a steel string against a nickel-silver fret, a microscopic amount of metal is rubbed away. Over time, you’ll see "divots" or pits under the strings, usually around the first three frets where you play your open chords.
When these pits get deep, the guitar starts buzzing. You have two choices:
- A Level and Dress: A tech grinds all the frets down to the level of the deepest pit, rounds them off (crowning), and polishes them.
- A Refret: The old wires are pulled out with pliers, and brand-new wire is hammered in. This is "open heart surgery" for a guitar. It’s expensive, but it can make an old, beat-up instrument feel brand new.
Actionable steps for your guitar
Don't just stare at them; take care of them. If you want your frets to last and your playing to feel smooth, do these three things:
- Clean your frets: Every time you change strings, take a scrap of an old t-shirt and some Gorgomyte or very fine (0000) steel wool—if you cover your pickups with tape first—and buff the oxidation off. Shiny frets feel faster.
- Watch the humidity: Keep your guitar in its case with a humidifier during the dry months. This prevents the "sprout" and keeps the neck stable.
- Check for "High Frets": If your guitar buzzes on one specific note but not others, you likely have a fret that has "popped up" slightly. You can check this with a "fret rocker"—a small straight edge that spans three frets. If it rocks back and forth like a seesaw, the middle fret is high and needs a professional tap back into place.
Understanding what is a fret on a guitar changes how you look at your instrument. It’s not just a decoration; it’s the bridge between your fingers and the physics of sound. Treat them well, and they’ll stay out of your way so you can actually make some music.