12-string guitar strings, explained: octave courses, lighter gauges, and the sets that fit

A 12-string sounds like two guitars playing at once because, in a way, it is. The extra six strings are not there for range. They are there to double the six you already know, and the doubling is what gives the instrument its huge, shimmering, slightly out-of-phase ring. It is the sound of a Rickenbacker on 'A Hard Day's Night,' a Byrds single, a Tom Petty chorus, the open jangle that a six-string simply cannot make on its own.

The whole effect comes down to how the strings are arranged, and once you see the layout the rest of the instrument makes sense. There is no exotic tuning to learn and no special technique at the strumming hand. The magic is built into the set of strings itself. So that is where we will start.

A 12-string is organized into six courses. A course is a pair of strings, set close together, that you fret and pick as if they were one. You play six courses the way you play six strings, but each press of a fingertip sounds two strings instead of one.

The pairs are not all the same, and this is the part worth understanding. The top two courses, the B and the high E, are tuned in unison: both strings of the pair are the same gauge and the same pitch (D'Addario). They thicken those high notes without changing them.

The lower four courses are where the shimmer lives. The low E, A, D, and G are each paired with a much thinner string tuned a full octave higher. On D'Addario's acoustic EJ38, the main G string is a wound .023 and its partner is a plain .008, an octave up; the low E is a .047 paired with a .027 (D'Addario). Strum a low chord and every bass note arrives with its own octave ringing on top. That stacked octave is the natural chorus you hear, and no pedal reproduces it quite the same way.

Here is the surprise for anyone moving over from a six-string. A 12-string set is lighter, not heavier. You would think twice the strings means a beefier pack. The opposite is true, and for a good reason: twelve strings under tension pull on the neck and the top with close to double the force of six. Left unchecked, that load warps necks and bellies acoustic tops.

So makers gauge down to keep the total tension in a safe window. D'Addario's most popular 12-string set, the light EJ38, runs from a .010 high E to a .047 low E (D'Addario). Compare that to a six-string light set like the D'Addario EJ16, which runs .012 to .053. The 12-string "light" is genuinely lighter than the six-string "light." If you want even less load, an extra-light set like the EJ41 drops to a .009 top, which suits a vintage or lightly braced instrument (D'Addario).

Many players go a step further and tune the whole guitar down a half or whole step, then capo up to pitch when a song needs it. It is an old habit, as old as Lead Belly, and it spares both the instrument and your fretting hand the full brunt of twelve strings at concert pitch.

Most 12-strings are acoustic, and most acoustic 12-strings want phosphor bronze. It is the warm, balanced, long-lived alloy that D'Addario introduced to acoustic strings back in 1974, and it has been the default acoustic wrap ever since (D'Addario). On a 12-string, that warmth keeps the doubled octaves from turning brittle or harsh.

The standard set is the D'Addario EJ38, a light phosphor bronze 12-string set and the most popular 12-string set the company makes. Reach for the EJ41 extra light instead if your guitar is old, small-bodied, or you simply want a slinkier feel. Both are dedicated 12-string packs, which is the key point: they include the four thin octave strings that no six-string set contains.

A note on buying the dedicated sets. We do not have our own verified buy page for the EJ38 or EJ41 yet, so the links above go straight to D'Addario's own product pages. A CYS catalog page for the 12-string sets is on the way. The D'Addario EJ16 phosphor bronze set in the sidebar is the verified six-string set we stock today, and it is the right thing to grab when one string of a course breaks and you do not want to change all twelve. For the full acoustic shelf, browse our brand-by-brand catalog.

The electric 12-string is a smaller club, but it owns some of the most recognizable tones in rock. This is the Rickenbacker 360/12 sound, the chiming intro that George Harrison put on 'A Hard Day's Night' with his 1963 model, and the texture that Johnny Marr and others carried into jangle and indie decades later.

For electric, the common choice is the D'Addario EXL150, a regular light nickel wound 12-string set running .010 to .046 (D'Addario). Nickel-plated steel keeps the top end bright, which is exactly what you want from a jangle machine: the octave strings need treble to sparkle. The course layout follows the same rule as the acoustic, unison on the top two pairs, octaves on the lower four. As with the acoustic sets, we will point you to D'Addario directly until our own page lands.

There is a clever side door worth knowing, because it lets a six-string borrow the 12-string sound. It is called high-strung, or Nashville, tuning. You string a normal six-string with only the thin octave strings from a 12-string set, so the bottom four strings jump up an octave while the top two stay put.

On its own it sounds thin and bell-like. Layered under a normally strung guitar playing the same part, it fakes the shimmer of a true 12-string in a recording, which is why session players have leaned on it for decades. You do not have to build the set by hand. D'Addario sells it ready-made, the EXL150H for electric and the EJ38H for acoustic (D'Addario). It is the cheapest way to get a taste of the doubled sound without owning a twelve.