You know C, D, E. You use them every day to tune, read tabs, name chords. But do you know why there are 12 notes and not 7? And why we say Do in French and C everywhere else online? In the next few minutes, the logic behind notes will be crystal clear. And your fretboard will make a lot more sense.
The essentials in 30 seconds
Western music uses 12 notes, each separated by a half step, the smallest distance in our musical system. The 7 natural notes (C, D, E, F, G, A, B) are completed by 5 altered notes (sharps or flats), all equally legitimate. On a guitar, one fret corresponds exactly to one half step: the neck is a regular sequence of these 12 notes, repeating identically at each octave.
1. How many notes in music? 12, not 7
We all learn C D E F G A B. Seven notes. Except if you count the frets on your guitar, something doesn’t add up: between the open string and the 12th fret, there are twelve steps, not seven.
The reality: Western music divides the octaveInterval between a note and the note of the same name at double frequency (2:1 ratio). into 12 pitches. We give simple names to 7 of them, the natural notes: C, D, E, F, G, A, B. The 5 remaining are named from their neighbors, with a sharpThe # symbol: the note one half step above the natural. (#, one half stepThe smallest distance between two notes; one fret on guitar. above) or a flatThe b symbol: the note one half step below the natural. (b, one half step below). These are the altered notes.
An important point: these 12 notes are all equal. C# isn’t an “extra” or “special” note. It’s a note just as normal as C. The natural/altered distinction comes from notation, not from sound. In the article about sound, you saw why each note corresponds to a precise frequency: the 12 notes are simply 12 organized frequencies.
You’ll notice on the circle that the dark circles show two names: C# and Db, for example. That’s not a mistake. C# and Db designate the same pitch (on your guitar, the same fret), but carry different names depending on the musical context. This is called enharmonicTwo names for the same pitch (for example C# and Db). equivalence. Like a word that would have two spellings depending on the sentence. The choice of name follows a logic we’ll see when building scales from whole and half steps.
But why 12, anyway?
Not by chance, and not “because it sounds good.” The reason is acoustic. If you go up by fifths (the most consonant interval after the octave, we’ll discuss it in the article on intervals), you need exactly 12 jumps to return to your starting point, a few octaves later. That’s where the 12 notes come from.
Small detail that kept theorists busy for centuries: this stacking of fifths doesn’t fall back perfectly in tune. To make everything work out, we slightly rounded each half step to divide the octave into 12 rigorously equal parts. This tuning system is called equal temperament, and it’s what makes your fretboard perfectly regular: each fret equals exactly the same interval, everywhere.
2. The half step: the smallest distance in music
The half step (also called semitone) is the smallest pitch interval in the Western musical system. On your guitar, it has an immediate physical translation: one fret. Moving up one fret on any string raises the note by one half step. Always. Everywhere on the neck. That’s equal temperament in action.
Two half steps form a whole step (or whole tone), which is two frets. And here’s where the system reveals its structure: between most neighboring natural notes (C-D, D-E, F-G, G-A, A-B), there’s a whole step. But between E and F, and between B and C, there’s only a half step. One single fret.
Remember this rule, it’s the only one in the whole article: whole step between natural notes, except E-F and B-C. Everything else follows from that.
3. Why there’s no sharp between E and F (nor between B and C)
This is THE question every guitarist eventually asks. The answer fits in one sentence: E and F are already a half step apart, the smallest possible distance. There’s physically no room for a note between them. Same thing for B and C.
Everywhere else, the naturals are separated by a whole step: there’s a half step left in the middle, and that’s where an altered note slips in (C#/Db between C and D, for example).
The piano keyboard makes this irregularity visible: look where there’s no black key.
And this is one point where your guitar is clearer than the piano, on this specific question of distances: the fretboard makes no visual distinction between naturals and altereds. One fret = one half step, period. The keyboard’s irregularity disappears in the regularity of frets.
4. C or Do: Anglo-Saxon notation explained
Am. G7. Em. If you’ve ever searched for a tab or chord chart online, you’ve encountered these names. This is Anglo-Saxon notation: the same notes as Do Ré Mi, designated by letters. It’s not another musical system, just another language.
Where do the two come from? Latin notation (Do Ré Mi Fa Sol La Si) comes from the first syllables of a medieval chant, the hymn to Saint John, a system attributed to Guido of Arezzo in the 11th century. The first syllable, Ut, became Do over time. Alphabetical notation (A B C D E F G) is an older letter counting system that starts with A (which is La), the reference note. That’s why A = La and not A = Do: the two series simply don’t have the same starting point.
Why know both? Because the vast majority of online guitar resources (tabs, software, chord names) use Anglo-Saxon notation. Am means A minor. G7 means G 7. This correspondence will serve you throughout the rest of the series, especially when we see how to read and build chords.
5. The guitar fretboard: a sequence of half steps
Walk through a string note by note
Take your low E string, the thickest one. Open, it gives E. Each fret raises it by one half step. Moving fret by fret up to the 12th, you go through the 12 notes: E, F, F#, G, G#, A, A#, B, C, C#, D, D#… and E. At the 12th fret, you find your starting note again, one octave higher: same name, doubled frequency, and the cycle starts over.
The rule for finding any note
The classic mistake is learning notes fret by fret, like a list to memorize. Wrong approach: it’s not memory, it’s logic. You only need two things:
1. The name of the open string (E, A, D, G, B, E, you already know them: you tune with them).
2. The distance rule: whole step (two frets) between naturals, except E-F and B-C (one fret).
With that, you can calculate any note, on any string. Example: A string, 7th fret. A + 7 half steps = E. Next time you read “7th fret A string” on a tab, you’re not playing a fret number, you’re playing an E.
Bonus that explains your tuning: the 5th fret of the low E string gives A, exactly the note of your open A string. That’s why you tune that way.
Exercise: name the 12 notes on your low E string
Grab your guitar. Low E string, fret 0: E. Move fret by fret and name each note up to fret 12, applying the rule. If you land back on E at fret 12, your count is right. If you land on something else, recheck E-F and B-C: that’s where everyone gets it wrong. The visual above has an exercise mode (“Hide names”) to self-correct, with sound.
To go further and practice spotting notes everywhere on the neck, Twelve Trainer, the training module of Twelve Assistant, works on this in a fun way, string by string.
On your guitar: three challenges this week
Challenge 1. Name the 12 notes on your low E string, frets 0 to 12, without looking at the article. Goal: all 12 in under 30 seconds.
Challenge 2. Same exercise on the A string. You’ll see: same 12 notes, different starting point. Each string follows exactly the same logic.
Challenge 3. Explain out loud why there’s no sharp between E and F. If you can say it in one sentence, you’ve got it.
Common questions about musical notes
How many notes are there in music?
There are 12 notes in Western music, not 7 as often believed. The 7 natural notes (C, D, E, F, G, A, B) are completed by 5 altered notes, located between certain natural notes: these are sharps and flats. These 12 notes are all equal: C# is as normal a note as C. After the 12th note, the cycle starts over one octave higher.
What’s a half step in music?
The half step (or semitone) is the smallest distance between two notes in the Western musical system. On a guitar, one half step corresponds exactly to one fret: moving up one fret on any string raises the note by one half step, always and everywhere on the neck. Two half steps form a whole step (or whole tone), the distance that separates most natural notes (C and D, D and E, for example).
Why is there no sharp between E and F?
Because E and F are already separated by just one half step, the smallest possible distance: there’s no room for an intermediate note. Same case between B and C. Everywhere else, natural notes are separated by a whole step, which leaves room for an altered note between them. On the guitar fretboard, this is directly verifiable: only one fret separates E from F, and only one fret separates B from C.
How do you translate Do Ré Mi into English notation?
The correspondence is as follows: Do = C, Ré = D, Mi = E, Fa = F, Sol = G, La = A, Si = B. Both systems designate exactly the same notes, only the language changes. Note the starting point: the Anglo-Saxon series begins with A, which corresponds to La and not to Do. Knowing this correspondence is essential for a guitarist, because the majority of online resources (tabs, chord charts) use Anglo-Saxon notation: Am means A minor, G7 means G 7.
How do you find notes on the guitar fretboard?
It’s not about memorizing each fret, but applying simple logic: start from the open string name, then count half steps, at one half step per fret. You only need to remember one rule: all natural notes are separated by a whole step (two frets), except E-F and B-C which are separated by a half step (one fret). At fret 12, you find the open string note again, one octave higher, and the cycle of 12 notes starts over. With this method, you can find any note on any string.
Summary
- 12 notes, not 7: the 7 naturals + 5 altereds (sharps/flats), all equal. The octave divides into 12 pitches.
- The half step is the smallest distance in the system. On your guitar: one fret, always, everywhere (thanks to equal temperament).
- Whole step between naturals, except E-F and B-C: the only rule to remember to find any note on the neck.
- C# and Db: same pitch, two names (enharmonic). The name depends on context, we’ll see the logic with scales.
- Do Ré Mi = C D E: two languages for the same notes. The alphabetical series starts from A = La.
You’re no longer playing fret numbers. You’re playing notes, and you know why they’re called what they are.
Spot these 12 notes on your neck
You just understood the logic. The Fretboard Explorer displays and plays any note on the neck, fret by fret. No account, no credit card.
Open the demoNext in series
You now know there are 12 notes and that the half step is their unit of distance. The logical next step: what happens when we measure the distance between two notes? It’s called an interval. And that’s what we build everything else with: melodies, chords, scales.
Article 3: Intervals → ← Previous: Article 1: Sound and Pitch · Back to music theory table of contents