Notation & Symbols

Bar Line

Definition

A bar line is a vertical line drawn across the staff to divide music into measures (bars). Variants such as the double bar line, the final bar line and repeat bar lines mark sections, endings and repeats.

A bar line is a thin vertical line drawn from the top line of the staff to the bottom line. Bar lines cut the music into measures (bars) of equal length, as set by the time signature, so you can see where each group of beats begins. The first beat after a bar line is the downbeat.

Two treble-clef examples in 2/4. The first has four bars separated by a single bar line, a double bar line and, at the end, a thin-thick final bar line. The second has two bars enclosed by repeat signs with dots facing the music inside. — Left: a single bar line after bar 1, a double bar line after bar 2 and a final bar line at the end. Right: a pair of repeat bar lines; the two bars between them are played twice.

Kinds of bar line

Single bar line: a thin line between ordinary bars.
Double bar line: two thin lines, at the end of a section or just before a change of key, meter or tempo.
Final bar line: a thin line followed by a thick one, at the end of a piece or movement.
Repeat bar lines: thick and thin lines with two dots, the repeat sign that tells you to play a passage again.
Dashed bar line: now and then used to split a long bar into easier-to-read parts without changing the meter.

What a bar line does, and does not do

A bar line is a guide for the eye, not a pause: the music runs straight through it, unless a fermata or a caesura says otherwise. One important rule is attached to it, though. An accidental lasts only until the next bar line, so a sharp in one bar does not carry into the next, unless a tie carries that note across.

Bar lines across several staves

In piano music, bar lines usually run straight through both staves of the grand staff, tying the hands together visually. In choral music they are usually drawn through each staff separately, leaving the gaps between staves free for the words. In an orchestral score, they usually join the staves of each instrument family.

Bar lines also give the music its numbering. Many editions print a bar number at the start of each system, so a teacher can say "start at bar 17" and everyone finds the same place.

Practice with Add the Barlines and Complete the measure.

Common questions

Is it bar line or barline?

Both spellings are common and mean the same thing.

Does a bar line cancel an accidental?

Yes. An accidental lasts until the end of its bar. After the bar line the note returns to the key signature, unless it is tied across the bar line.