I'm relatively new to reading piano score and I notice lots of little subtle things about it which have great importance. One feature I wonder if it is ever used with special importance is number of bars per line/row. The published books of game music I have seem pretty consistent within a song, tho it may differ across the whole book. normally 3-5 bars/measures in a single row.

Sometimes when reading a score found online it would go from consistently 4 bars but then suddenly one line has only a single bar/measure... in some cases this makes sense to me

  1. if the measure was very note dense (so more space per note makes better readability)
  2. aligning with other voices which have denser notes
  3. if the measure was thematically different in some way (flats/sharps ect)
  4. really long volume bars (crescendo arrows) indicating a large increase over a single measure (tho you could also use p/m/f to indicate the degree of absolute volume change)

Are there any other (valid) reasons to do something like this? Does it bother anyone else? I'd prefer it was at least consistent in a song to make it easier for timing tracking to be consistent as I read. To me it's so disruptive that it is this something I may bug report over? Am I just over reacting here? I just don't know something important I assume, and maybe there are good reasons to do this.

I notice this in a lot of pieces, and one in particular is: https://musescore.com/nicolas/scores/437 This score alternates between 3 measures per line and 1 measure per line hummelflug first two lines of sheet music This goes on thru the whole song. I don't see any clear reason why it does that. Seems odd to a noob like me... Maybe it's just poor generation? some computer produced effect? ie something like a line justify, so if it's going to take 2 pages anyway, it just averages the measures out across the page... idk... doesn't seem like a great theory... so I downloaded the song and view it in musescore app, and the effect is (almost) gone, So I guess it's just something in the musescore web app viewer... However there is still a few measures where it displays like that even in the windows app... and the way it split the song across pages is really odd... but now i'm probably getting off topic.

I think this question was trying to ask something similar but it was worded really poorly: How many measures/bars per staff?

Ok, so maybe my example could be explained for a variety of reasons... But I think it's still a valid question. Maybe to someone with more insight this could be obvious.

TLDR; Is there any functional musical reason (or other valid reason) why you would change the number of measures per line?

PS by use of "line" I mean a single row on a sheet. I'm a noob so IDK what musical line means.

  • 4
    The problem is MuseScore. This is an amateur rendition of the piece and not well put together.
    – Aaron
    Dec 11, 2022 at 22:13
  • @Aaron To be specific the problem is that MuseScore does allow setting of break points, but it does not allow to forbid breaks elsewhere. Thus the creator of the score intended for four measures in the first system. But due to probably a slight difference in dimensions for the online score we get an automatic break, MuseScore uses a greedy algorithm (pack each consecutive line as much as possible), so you then get single measure systems. Really what MuseScore should do is to disable automatic breaks in this case, changing spacing if necessary.
    – Lazy
    Dec 11, 2022 at 22:51
  • @Lazy Also to be specific, I was referring to MuseScore the website, not MuseScore the notation software. You are correct about the software, of course.
    – Aaron
    Dec 12, 2022 at 0:04
  • @Aaron This is user error, not MuseScore error I think!
    – Laurence
    Dec 12, 2022 at 1:11
  • 2
    @Laurence No, because this is not what the user intended when they wrote the score, but MuseScore.com reflows the whole thing while keeping the user instructions leading to such an error. The user cannot do anything against this except removing all manual breaks and leaving the decision of where to break completely to MuseScore. So it is not an user error, but a lack of control capability for MuseScore.
    – Lazy
    Dec 13, 2022 at 7:39

3 Answers 3


The musical term for what you are calling a line/row is a system.

The number of measures/bars per system doesn't necessarily* have any musical meaning. Often as many measures as possible per system is used — to save on paper and page turns. But readability is important too, and the music notation shouldn't get too squashed.

In the example piece above, what I think has happened is as follows:

  • The person who made that score had a MuseScore setting that automatically makes system breaks every 4 measures.

  • But, because that piece is full of semiquavers/sixteenths and accidentals (which take up lots of horizontal space) MuseScore decided that after 3 measures the system was full, and there needed to be a system break (to stop the the notation from getting too squashed).

  • Both of theses rules don't work well together (for this combination of music piece, staff size, and paper size) and results in systems alternating between 3 and 1 measures. This doesn't have any musical significance to this piece of music, and just looks terrible.

It can easily be fixed: by turning off the automatic system breaks, by making system breaks every two measures, by making the staff size smaller, or by making the paper size larger. All of theses fixes are relatively easy to do in MuseScore; it's not a bug with the program, the user probably just didn't know how to do any of these (or didn't care how it looked).

* Personally, I do try to use system breaks (and page breaks) at significant points in the music when possible: at the end of phrases, sections, etc. places that make the structure of the music easy to see. For lots of music this will be a break every 4 measures, but this is only because this is how the music is often structured. If a section of the music is structured in 3 measure phrases, I would try to have system breaks every 3 or 6 measures.

  • 1
    The problem here is of course that decision of automatic breaks might change over different versions of MuseScore, and between MuseScore (the application) and MuseScore.com.
    – Lazy
    Dec 13, 2022 at 8:24
  • When writing out a chord chart, I systematically write 4 bars per line. Bit like a lot of poems. Which after all, is what a lot of songs emanate from, sort of. Writing that way seems to match most songs, so the reader knows where they are more easily. That's by hand, and by the way.
    – Tim
    Dec 13, 2022 at 11:54
  • @Lazy - That's a good explanation, I didn't think of that. Dec 13, 2022 at 11:58

Brief answer, this is user error.

The basic rule is simply 'let it flow'. Notation programs generally make a pretty good job of this, spacing things out so as to maintain a readable and attractive note density.

'Let it flow' sometimes needs manual modification. Sometimes (but not, perhaps, quite as often as many writers imagine) fixed 4-bar lines are appropriate. It's nice to have a section-ending double bar or repeat barline come at the end of a system. And in instrumental parts (it's rarely possible in a piano score) we try to arrange convenient page turns by - when there ARE a few bars rest - placing them just before a page break.

None of this applies here. It's just bad engraving. And it's not MuseScore's fault. Although free, it's a perfectly competent program. But, because it's free, it attracts more inexperienced users than Finale or Sibelius. I don't think MuseScore would have offered this layout as default. But even if it did, the user should have improved it! Here's a standard edition of 'Bumblebee'. Nothing controversial about the layout. It's just obviously how it SHOULD be laid out!

enter image description here

And here's a quick test done in MuseScore. With no manual intervention, it does what it ought to. But even if it hadn't - it's been suggested that a few more accidentals could force a line break - that's not really the point. MuseScore was given conflicting instructions. 4 bars per line, but too many symbols to fit into one line. The user should have reconciled this before publishing.

enter image description here

  • When I tried entering the upper stave's four measures (as posted in the question) into MuseScore: the last few accidentals made the system spill. Your "test" saves on accidentals by using a different key, a key signature, and different enharmonic spellings — from the score in the question, and from the other version in your answer. Dec 12, 2022 at 16:04
  • 1
    I’m downvoting thing answer, which is something I do not like to do, but this answer is incorrect and missleading. As Elements said your "test" has nothing to do with the original score except for having 16th, and if you use the actual notes from the Score MuseScore will break the last measure (due to 2 extra accidentals). Then this is not a user error. If you download the score you can see that the user manually places line breaks in "good" positions, and you will see that this problem does not happen in MuseScore (it happens in other places though, so probably MuseScores layout changed)
    – Lazy
    Dec 13, 2022 at 7:53
  • 1
    since the version in question. But we see this problem in fact only affects the display on MuseScore.com, which shows us that there is a slight difference in spacing. The point is: When the user created the score he manually optimized the layout to get what he wants, but as soon as MuseScores layout changes slightly this gets messed up and needs to be optimized again. This is not an user error, as the user cannot do anything against it. It is lack of stability options of MuseScore. This would not happen if we could forbid MuseScore to do automatic breaks for example.
    – Lazy
    Dec 13, 2022 at 7:56
  • 1
    Then the part of the basic rule being "let it flow" is quite frankly nonsense. In a traditional publishing routine specifying line breaks is responsibility of the editor and requires quite some thought. This includes thing such as: Even density of notes, even density of staves per page, number of pages needed to print the score, good positions for page turning, the general aesthetics (e.g. it looks bad to have a repeat bar very short after a break, or to have a tempo marking on the last bar in a system), and much more. This is not a trivial task!
    – Lazy
    Dec 13, 2022 at 8:04
  • 1
    Now, "let it flow" could be a good description of MuseScore’s greedy algorithm. By spacing the elements of a bar with some "spring" each system has some amount of compressibility. Then you just start adding bars to the system until it cannot be compressed further, at which point you start a new system. This is a computationally simple algorithm, but it also does not produce particularly nice results.
    – Lazy
    Dec 13, 2022 at 8:14

There is one notable perceptional effect: if the staves (lines) are too similar, the human reader might encounter problems to identify in which line to continue. (Laurence's example demonstrates this quite well, which to a certain degree would be remedied by adding the different dynamics)

I remember a statement from the lilypond motivation basics, that in those cases the number of bars is a useful controlling parameter to achieve a slight variation. In your example the second line is of course completely exaggerating this idea.

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