What do the numbers in a time signature mean?

The top number is beats per bar. The bottom number is the note value of each beat (4 = quarter note, 8 = eighth note, 2 = half note). So 4/4 means 4 quarter-note beats per bar. 6/8 means 6 eighth-note beats per bar (usually felt as 2 groups of 3).

What is the most common time signature?

4/4 is by far the most common, used in virtually all pop, rock, electronic, hip-hop and R&B music. 3/4 (waltz time) is the second most common. 6/8 is popular in ballads and folk music. Odd time signatures like 5/4 and 7/8 are used in progressive rock and jazz.

How does BPM relate to time signature?

BPM traditionally refers to quarter-note beats per minute. In 4/4, each beat is a quarter note, so 120 BPM = 120 quarter notes per minute. In 6/8, the beat is usually a dotted quarter (3 eighth notes), so 120 BPM in 6/8 means 120 dotted quarter notes per minute (= 360 eighth notes per minute).

How long is a typical song in bars?

A typical pop song at 120 BPM in 4/4 is about 80-120 bars (2:40-4:00). A verse might be 8-16 bars, a chorus 8-16 bars. An intro and outro are typically 4-8 bars each. Electronic music tracks are often 64-128 bars (2-4 minutes) with longer buildups.

AudioCalcs

Time Signature Calculator — Bar Length & Song Time

Calculate bar lengths, beat durations and total song time from time signature and BPM.

Beats Per Bar (top number)

Beat Unit (bottom number)

4 = quarter note, 8 = eighth note

BPM

Number of Bars

How We Calculate This

Beat Duration

Beat (ms) = (60,000 / BPM) × (4 / beat unit)

If the beat unit is 4 (quarter note), beat duration = 60,000 / BPM. If the beat unit is 8 (eighth note), it is half that.

Bar Length

Bar (ms) = Beat duration × Beats per bar

Total Time

Total (s) = Bar length × Number of bars / 1000

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates based on standard formulas. Always verify results for critical applications.