17-fret or 19-fret tenor banjo?

Does fret count tell you the scale length?

No, and that is the trap. Everyone shopping for an Irish tenor banjo meets this question in the first ten minutes, and almost every answer treats 17-fret and 19-fret as if they were two fixed sizes. They are not. They are labels, and the sizes underneath them overlap and disagree.

One widely cited account puts the short-scale 17-fret at 20 to 21.5 inches and the long-scale 19-fret at 22 to 23. Discussion among players who own several puts the 17-fret lower, at 19 to 20 inches, and notes it can go shorter still. Those two accounts differ by more than two inches at the short end, which is a larger gap than the one between a long 17-fret and a short 19-fret.

So the useful thing to do is stop asking how many frets and start asking how long the scale is. That is one measurement, from the nut to the bridge, and any seller can give it to you. If they cannot, that tells you something too.

What is the difference between a 17-fret and a 19-fret?

You are trading reach for tone. That is the sentence most pages talk around. A 19-fret asks your left hand to cover 16% more distance everywhere on the neck, and it gives you a louder, fuller, deeper instrument in exchange. That is the whole decision.

The reach figure is not an estimate. Fret positions are a fixed proportion of scale length, so every span on a 23 inch neck is exactly 16.5% wider than the same span on a 19.75 inch one. The first fret is 33mm wide instead of 28mm. A four-fret span in first position, which is the shape almost every Irish tune sits in, goes from 4.07 inches to 4.74 inches.

That two-thirds of an inch is what people are describing when they say a 19-fret is harder to play fast. On a short scale one finger covers two frets and the hand does not move. On a long scale the same passage may need the little finger brought in, or a position shift for a note you would otherwise have reached without thinking. Neither is difficult in isolation. Both cost time at speed, and Irish tunes are played at speed.

Does a 19-fret tenor banjo sound better?

Yes, it is louder and fuller, and that is the reason the players who most want to be heard use the longer scale.

The mechanism follows from the same arithmetic as the reach. A longer string at the same pitch is heavier and sits under about a third more tension, and that extra tension goes into the bridge, which sits directly on the drum head. More energy into the head means more volume and a quicker, snappier attack. Players describe the difference as a richer bass and a fuller voice, and a short scale as thinner underneath.

The low end is where you hear it most. Frequency response follows string length, so shortening the scale narrows what the bottom string can give you, and on an instrument tuned down to a 98 Hz G that is exactly where the sound has least room to spare. A short-scale G can sound slack and hollow where a long-scale G sounds like a note.

That is what a professional is buying. In a loud session, on a stage or on a recording, the long scale carries. Sitting at home learning Out on the Ocean, it is a difference you may not care about for a year.

What does scale length actually change?

String tension, and it changes it with the square of the length. That one relationship explains every complaint people have about short-scale banjos in GDAE, and nobody in the category publishes it.

A vibrating string at a fixed pitch carries tension proportional to the square of its speaking length. Take a 19.75 inch scale against a 23 inch scale. The ratio is 0.859, and squaring it gives 0.737. The same string, tuned to the same note, sits at about 74% of the tension. A quarter of the tension is gone.

That is why the low G goes slack on a short scale, and the low G is the one that suffers most because it is already the loosest string on the instrument at 98 Hz. It is also why people report intonation trouble: a slack string goes sharp more readily when you press it down.

The fix is heavier strings, and the arithmetic tells you how much heavier. To hold the same tension you need the string to weigh proportionally more per unit length, which for a plain string means the diameter goes up by the same ratio as the scale went down. From 23 inches to 19.75 that ratio is 1.165, so every gauge goes up by about 16%.

What string gauges does a short scale need?

Roughly 16% thicker than a long-scale set, right across all four strings. A rule is worth more if it predicts something, so here is the test. Here is the test. Take a published GDAE set for a 23 inch 19-fret instrument, scale every gauge up by 1.165 for a 19.75 inch scale, and compare the result against the set a player reports using on exactly that instrument.

Three of the four land within a thousandth of an inch. The bottom G comes out close to two thousandths light, which is the direction you would expect, since a slack low string is the one people deliberately overshoot.

The honest caveat: these are two individual setups reported on a discussion forum rather than a controlled measurement, and the second string is wound, so its weight does not scale with diameter the way a plain string does. The rule has no business being that accurate on a wound string. Treat the table as a starting point for a string order rather than a law.

Why choose a 17-fret banjo?

It is not about small hands, although that gets said most often. The short-scale tenor was made in the 1920s for mandolin players who wanted to double on banjo, and that is still the strongest reason to want one.

On a short scale each left-hand finger covers two frets, which is mandolin and fiddle fingering. The tune falls under your hand in the same shape and you phrase it the same way, because you are not shifting position to reach notes a fiddler takes in one hand position. If you already play mandolin, that is a large amount of transfer you get for free.

A long-scale 19-fret asks you to chord and finger more the way a guitarist does, with position shifts a mandolin player has never had to make. It is learnable. It is just not free.

Why do players disagree about 17 and 19 frets?

Because two different groups are answering and nobody says which one they are in. Once you see that, the disagreement stops being a disagreement.

Among top-level players the 19-fret is the clear standard. Among beginners and amateurs the short scale is the more popular choice, and shops selling into Irish music say the majority of Irish-style buyers take the 17-fret. Both statements are true. They are describing different people.

The reason is the tension arithmetic above. A 19-fret at the same pitch carries roughly a third more tension than a short scale, and tighter strings are physically harder to press and harder to play cleanly at speed when your hand is new to it. That advantage of the short scale fades as you put hours in, which is precisely why the people with the most hours have stopped caring about it.

The instrument that defined the sound was a long scale. Barney McKenna played a 19-fret four-string resonator tenor, and the Dictionary of Irish Biography credits him with revolutionising the technique of exactly that specification and establishing the instrument in the tradition. Most of what a beginner hears as the Irish banjo sound is a 19-fret.

One thing that does not change either way: there is no musical difference. Same notes, same chords, same tunes, same tab. Nothing is playable on one and impossible on the other. The difference is entirely physical.

Which one should you buy?

If you already play mandolin or fiddle: 17-fret. One finger covers two frets, the tunes fall in the shape your hand already knows, and you skip a re-learning step that has nothing to do with music.

If you have small hands: 17-fret, and it is the clearest case on this page. A 5.14 inch stretch from the second fret to the seventh is not available to every hand. The same stretch on a short scale is 4.41 inches.

If you want the recorded sound and you intend to play out: 19-fret, 22 to 23 inches. It is louder, deeper and it carries, and it is what almost every player you have heard is using.

If you have no idea yet: 19-fret at the shorter end, around 22 inches. It is the standard, the strings are easier to buy, second-hand supply is better, and it holds its value. The reach is learnable and the tone is not addable.

And whichever you buy second hand: measure it, or make the seller measure it, then order a GDAE set matched to that scale rather than a generic one. A short-scale instrument strung for a long scale is the single most common reason a second-hand banjo feels dead.