As I understand, the quarter note is a note that lasts for one beat.

the half note, is a note that lasts for two beats,

the full note, is a note that lasts for four beats,

now i get that, but what is the length of one beat? is it standard? does it differ from instrument to another ?

I'm using virtual piano http://virtualpiano.net to practice

  • There is a difference between defining a unit of measure of time and a specific time measurement (even though that sound like double talk). It's because the word "measure" is used in two ways. A quarter note = one beat only in the signature X/4 (the 1/4 is the quarter and there are X in a "measure" of music). This is the same for all instruments. But the "length of a beat" is determined by tempo, how fast or slow you count the beats in real time. The length of one 1/4 note at 260 bpm is different that in 60 bpm.
    – user50691
    Jun 1, 2018 at 16:56

3 Answers 3


The duration of the beat is set by the tempo marking, usually an italian word like lento, andante, vivace, etc. that you may have noticed at the beginning of musical scores.

These words correspond to an approximate setting of beats per minute (bpm), that you find for example in wikipedia and is usually also marked on the scales of metronomes. But the performer or conductor must make is own judgement as to the precise tempo to use.

So, for example, an andante tempo marking is considered to be somewhere between approximately 76 and 108 bpm. Taking 90 bpm as example, for a 4/4 time signature:

  • 4 beats/measure
  • 1 beat = 1 quarter note
  • 1 quarter note = 1 metronome beat at 90 bpm (so 1/90*60 = 0.67 seconds/beat, but measuring rythmic-units duration's in seconds is not something usually very useful musically).

Now, something to keep in mind is, metronome scales and conventional bpm ranges for tempo markings do indeed assume a beat unit of a quarter note, but that's not always true. The time signature used for each piece defines, in its lower number, what rhythmic unit corresponds to a beat (many times a quarter note, yes, but also frequently an eighth and some times a half note, or other values).

For example, for a 3/8 time signature (not very frequent, but for the sake of example) and the same andante tempo marking:

  • 3 beats / measure
  • 1 beat = 1 eight note
  • 1 metronome beat = 2 measure beats, if you set the metronome to 90 "quarter notes/minute". So in this case, to mark the actual beat, the metronome should be set to 180.

This is important, as the beat unit defines the intended musical "pulse" of the piece, so it's not the same thing a "pulse" of 3 quarter or of 6 eight notes per measure, despite the overall measure duration resulting the same.

We should also refer the case of compound time signatures, where a beat is a dotted rythmic note. For a 6/8 time signature:

  • 2 beats / measure
  • 1 beat = 3 eight notes = 1 dotted quarter note
  • 1 metronome beat = 1.5 measure beats. So in this case, to mark the actual beat, the metronome should be set to 135.

To avoid any confusion and provide more precise performance instructions, since the invention of the metronome some composers provide tempo markings in precise bpm.

  • Kindly what did you mean by 4/4 measure ? what I know is a quarter note lasts for one beat while full note lasts for 4 beats, is that what you meant by 4/4? and if it is 3/3 measure, does that mean the full note is 3 beats? in that case what would a quarter note mean? I still have some questions about your answer but i need to understand this first then i will continue with you, many thanks for the efforts May 9, 2016 at 10:30
  • Marco, 4/4 is short hand for a time signature where in the score two large numbers appear on on top of the other. Just to put you on the right track, the number below indicates the rythmic unit for the beat (4 for a quarter note, 8 for an eight note, etc.); the number above indicates how many units in each measure. This chapter cnx.org/contents/[email protected]:aBABIQ76@16/Time-Signature explains time signatures rather well. May 9, 2016 at 12:56
  • The link above belongs to a book that's an excellent (and free) introduction to basic music theory. You can download the whole book (and I advise to that do it) from here cnx.org/contents/[email protected]:_GmJ4ENa@7/…. May 9, 2016 at 12:56

One beat is as long as the composer says it will be. Usually signified at the beginning of a piece with 'bpm', This stands for beats per minute, so if it stated 60bpm, there would be one beat every second.A tune twice as fast would be 120bpm. No-one actually times abeats per se, but instead would use a metronome to set the speed of the piece.It's also very important that the composer states what that 'beat' actually is - it could be, and usually is, a crotchet, but could be a dotted crotche or quaver or minim. Dance tunes in particular will have a bpm that needs adhering to, whereas a lot of classical pieces will not have an exact metronome mark, but will say 'andante', 'presto', 'largo' instead. These are vague on purpose to give performers a margin in which nto work. With modern pop type music, in order to keep everyone in time, a cick track is used - it's a sort of metronome, and means that if recordings are done at different times (or even different countries!), the beat will remain constant.

  • Thanks for answering, but instead would use a metronome to set the speed of the piece ... what does metronome mean please? it could be, and usually is, a crotchet, now I'm confused, look at this page they said crotchet is the name of the quarter note, not the duration of the beat. but will say 'andante', 'presto', 'largo' instead yes I've seen that millions of times, but how can the players know the actual bean then? (continue next comment) May 9, 2016 at 9:32
  • the opening four notes ta ta ta taaaaa in the 5th symphony will be so different if we don't know the actual beat time, and in face the same four notes were used again, at least, in the third movement May 9, 2016 at 9:32
  • Oh dear! A metronome is a timing instrument, the originals were like a miniature grandfather clock upside down. The pendulum has a movable weight on it, so sliding it up slows the metronome down, and vice versa. It has bpm marks to guide the user. Despite what you read, the crotchet (quarter note) CAN BE and OFTEN IS the beat. Beethoven's (presumably) 5th symphony actually starts with an anacrucis, so is probably not a good example. The tempo (speed rating) at the beginning of each movement tell how fast/slow to play it, so there's no problem cont.
    – Tim
    May 9, 2016 at 10:13
  • there, and as I said, they're left vague to give a rough idea, but allow musical licence. Metronomes are readily available , even apps for the phone give free ones. Nowadays, electronic ones which tick, click and ting are the most common.
    – Tim
    May 9, 2016 at 10:14
  • "These are vague on purpose" - Actually they weren't totally vague. Before the metronome was invented (in about 1815) there was a fairly well-known set of "rules" for relating the tempo of the conventional terms like Presto, Allegro, Andante, etc to the human pulse rate. The nominal speeds were 40, 60, 80, 120, and 160 beats per minute, based on an "average" pulse rate of 80. Of course there was some variation around each of those nominal values. "Old-style" mechanical, clockwork metronomes were marked with the terms like Allegro as well as in beats per minute, following these conventions.
    – user19146
    May 10, 2016 at 4:21

The answers above are correct, but only with regards to post-baroque music, which is when tempo indications began to mean absolute tempo with regards to the time signature. In baroque music, on the other hand, oftentimes the time signature is not an indication of what the core rhythmic unit is. An example could be the first movement of Georg Philipp Telemann’s ‘Sonata for two Flutes in A major’; for this, the tempo is written as andante cantabile and then time signature set to 2⁄4, but playing the piece at this tempo would surely ruin it.

The general rule for baroque music and earlier, is that the tempo is indicated for the rhythmically most important unit; this is usually the bass line. Listen to this [http://tidal.com/track/61413470] (Georgiev–Goranova–Ivanova recording) for an example; it is at roughly 85 bpm by the quavers (eight notes).

Summary: For early music, the time signature does not necessarily indicatewhat should be counted by the tempo indication; rather it is an indication of what the feel of the music should be. Combine that with finding the most important rhythmical pattern and apply the tempo to that unit, whilst trying to maintain a pace giving the feel of the time signature. Also note that having an indication at all of the tempo, is a sign that the beat should be straight, as opposed to an inégalité performance, as Das wohltemperierte Klavier is a good indication of (where only a couple of all the pieces have tempo indication. For inégalité, please view the article on Britannica (https://www.britannica.com/art/inegalite).

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