Frets are frets, right?
Well, sort of. For the most part, the frets we use in our instruments are made to essentially the same style: A rounded crown (the bit you see on the fretboard) and a tang protruding from it (the bit that gets jammed into the slot in the fingerboard). See Hastily Drawn Diagram™ below.
Where things can get a little different, however, is in sizes and materials.
For all intents and purposes, when most people think about fret-sizes, they’re thinking about the width and height of the crown. Frets can be sourced with different sized tangs but these are generally the realm of people like me who have to worry about fitting them to hacked-up slots or for ‘corrective refretting’ where the tangs are used to help control neck relief.
The crown width and height can make a difference to the average player, though.
In the context of this discussion, I don’t want to get into listing sizes—in thousands of an inch (yes, still imperial measurements)—of various fret wires. I’m going to stick with tall, medium and low descriptions for height and narrow, medium and wide for width. If you’ve questions about particular specifications, shout up in the comments and I’ll try to answer them.
Fret wire: Tall
Taller frets make string bends nice and easy as there’s plenty of ‘air’ beneath the string to let your finger get a good grip. Hammer-ons, pull-offs and the like are also easy. Think of a taller fret as a less extreme version of a scalloped fingerboard.
On the downside, taller frets can lead to intonation issues from players pushing too hard (with no fingerboard to stop them) and pulling the note sharp. Also, if you’re not used to them, they can feel like ‘steps’ as you slide along the neck. Moving to taller frets can be a learning curve for many players.
Obviously, though, you’ll generally get longer wear out of a taller fret and can have it levelled/dressed more often (although this latter benefit does mean your tall fret gets slightly shorter each time so that must be considered).
Fret Wire: Low
You’ve probably heard of the Gibson ‘Fretless Wonders’. This was a nickname given to some Les Pauls and SGs that came with really low frets. While these guitars often had very low action and little resistance in the way of that ‘stepped’ feeling you can get when you slide up and down the board, the downside was that they were more difficult to bend or pull-off as it was difficult to get under the string.
It’s relatively unusual to install really low frets these days (unless matching an existing fret) and, in my experience, most guitarists don’t actually get on with lower frets. Of course, the lifetime of a lower fret is going to be much shorter and it often won’t be possible to level more than once (if that).
Fret wire: Medium
The Goldilocks zone in my opinion. Think of this as a best of both worlds scenario. The majority of guitars come with medium frets installed and most of us are quite happy to play on them. If properly installed, they can usually be dressed a few times before a refret is required. If you’re unsure about fret height, medium is the way to go.
Fret Wire: Wide
Jumbo. Gotta go jumbo. Wide and (relatively) tall wire is often installed on guitars at the rockier end of the spectrum. A chunky, wide, wire can give a little more sustain and, if you’ve got a wide and tall wire, this can lend itself nicely to a rocky or a shreddy playing experience.
Wider frets wear a little more slowly so have more longevity. However, as they wear, they flatten on top and this can mean intonation problems creep in (effectively, the string begins to bear off a point closer to the bridge as the fret flattens).
Wide frets are almost exclusively the domain of the electric guitarist. It would be very unusual to see (or to fit) wide frets on an acoustic.
Fret Wire: Narrow
Narrow frets are relatively rare too, these days. You’ll see them on vintage acoustics a lot but even modern acoustics tend to err towards medium frets. Other instruments, like banjos and mandolins and the like often come with narrow frets (frequently very narrow). They can give a good clean tone but have slightly shorter lifespans.
Fret Wire: Medium
See above on Medium Height. Same goes for width. It’s a great place to be for most of us and, again, if you don’t know, you won’t go wrong.
Fret Size Impact on Tone
Different sized frets can have an impact on tone although I’ll give the usual caveat that tone is subjective and will remind you that you shouldn’t expect night-and-day differences. The changes you’ll get from different fret wire are typically very subtle.
Taller and/or wider frets have a bit more mass and this tends to translate as a tiny more sustain and a bit of an increase in ‘oomph’ (technical term). Narrower frets can sound cleaner or a little more well-defined. Remember, though: subtle.
Bottom Line: Is it worth upgrading?
If your current frets are worn and you’re in the market for a refret, it might be worth considering a different sized fret. As far as tonal changes go, don’t expect massive shifts. The real difference will be ‘feel’ and if a change is something you’re thinking about, it’s definitely a good idea to try out an instrument that already has your desired frets. You might love it and it’ll cement your decision or you might decide it’s not really for you.
Not sure if it helps, but I’d guess that more than 90% of the refrets I perform match the new wire to the old for completely understandable reasons. Sometimes, that comfortable pair of slippers is worth hanging on to.