If you buy a "cuatro" without saying which country you mean, you may get either of two instruments, and they have almost nothing in common. One has ten steel strings in five doubled courses, a keyhole-shaped body, and a bright ringing voice that plays melody with a pick. The other has four single nylon strings, a small guitar shape, and a job in the rhythm section. The shared name is a shared ancestor and a shared numeral, not a family resemblance — and this site refuses to write one page that covers both.
What follows is the difference stated in numbers rather than adjectives. Everything in the table is computed from the instrument registry's own pitches; nothing is asserted, and CI recomputes all of it on every build.
The two instruments, measured
| Instrument | Tuning | Strings | Open strings spell | Span | Fold |
|---|---|---|---|---|---|
| Puerto Rican Cuatro (Standard) | B-E-A-D-G | 5 | G major pentatonic | minor thirteenth | no fold |
| Puerto Rican Cuatro (Antiguo A-D-G-C-F) | A-D-G-C-F | 5 | F major pentatonic | minor thirteenth | no fold |
| Venezuelan Cuatro | A-D-F#-B | 4 | D6 | major sixth | perfect fifth down at the last pair |
The span column is the one that decides how each instrument sounds under a hand. The Puerto Rican instrument opens across minor thirteenth — room enough for a melody on top and harmony beneath it. The Venezuelan one opens across major sixth, and every grip on it comes out inside roughly that width. That is not a stylistic choice; it is arithmetic, and it is why one instrument states tunes and the other states rhythm.
One climbs, one folds
Only one of these tunings folds, and which one is the whole story. The Puerto Rican instrument's open courses climb at every adjacent pair — a perfect fourth each time, from the wound B of the lowest course to the G on top — so the highest string is the outermost one and a picked melody sits exactly where a stroke finishes. The Venezuelan instrument's open strings climb steadily to the top and then drop a perfect fifth at the very last pair, so the highest string is not the outermost one: a stroke reaches its top note early and the rest of the grip lands underneath it as a block.
The doubling on the ten-string does not change that order. Its two lowest courses are octave pairs and the top three are unison pairs — B2 with B3, E3 with E4, then A3, D4 and G4 in unison — so the octave strings ring above the course beside them and brighten the low end, while every course's own note still climbs. The charts on this site draw each course at that note.
This is why "the cuatro is a strummed instrument" and "the cuatro is a picked instrument" are both true and refer to different objects. Fold the top of the range back inside the sweep and you get an instrument that answers a chord all at once. Let the fourths climb all the way to the top and you get one that answers with a line.
The antiguo tuning, and what it is not
The Puerto Rican side carries two tunings, and this site gives them separate URLs rather than a dropdown, because the fingerings are shared and the pitches are not. Compared string for string, the older tuning sits every string exactly a major second lower — a constant offset, which is exactly what makes every grip transfer unchanged and every note name on the diagram differ.
That relationship is computed here, not quoted: two tunings count as transposed siblings only when their adjacent intervals match and every string differs by the same amount. If a future registry change broke either condition, this page would fail rather than keep claiming a shared fingering the pitches no longer support.
Two different jobs
The ten-string is a lead voice. In jíbaro music it plays the tune — seis and aguinaldo repertoire, fast melodic improvisation over a típico ensemble — and the doubled courses are what let a small instrument carry that melody over a room. Its charts here name a fret and a finger for every course, because a grip and a melody position are the same object on it.
The four-string is a rhythm section. In joropo it holds the harmony and locks the cross-rhythm with the maracas while the harp or the bandola takes the low end and the melody. Its charts here are blocks, and the interesting page attached to them is not another chord grid but the golpes — the strum bars, where the brakes are declared and the two counts are measured.
Why the name stuck
Both instruments descend from the small four-course guitars that Spanish and Canary Island settlers carried across the Atlantic, and both kept a name that counted the courses those ancestors had. The Puerto Rican instrument grew to five courses and did not rename itself; the Venezuelan one stayed at four strings and did not need to. Everything after that — the body shapes, the string materials, the tunings, the technique, the repertoire — happened separately, on different islands and mainlands, for different music.
So when this site says cuatro without qualification, it is naming a coincidence. Every page that says anything more specific says which instrument it means, and gets its numbers from that instrument's own row in the registry. Start from the ten-string chords or the four-string chords depending on which one is in the room.