A score tells you how many bars there are; the tempo tells you how fast the beats go. Multiply the number of measures by the beats in each measure and divide by the beats per minute, and you have the playing time – as long as the tempo stays steady. That is useful for planning a concert programme, timing a piece for an exam or competition, fitting a cue to a film scene or checking whether a song will fit a radio edit.
The time signature sets how many beats are in a measure: four in 4/4, three in 3/4, six eighth notes in 6/8. Many musicians count compound meters such as 6/8 and 12/8 in dotted-quarter beats (two or four per bar) – choose that option if your metronome marking is for dotted quarters. For unusual meters choose “other” and type the number of beats.
If your piece is written over several staves or systems of equal length – for example a lead sheet with 8 bars per line – enter the bars per staff and the number of staves. Repeats are not expanded automatically, so count repeated sections twice.
How to use the Music Duration Calculator
- Calculate
- Time signature
- Beats per measure
- Tempo counts
- Tempo
- Number of measures (per staff)
- Number of staves / repeats of this length
- Target duration
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Beats per measure come from the time signature (or your own value, divided by three for dotted-beat counting in compound time). Total beats = beats per measure × measures × staves; duration = total beats × 60 ÷ tempo. In “find tempo” mode the formula is reversed.
Worked example
A waltz in 3/4 has 48 measures and is played at 90 BPM. Total beats = 3 × 48 = 144; duration = 144 × 60 ÷ 90 = 96 s = 1:36. If the same 48 measures are written on 4 staves of equal length (4 × 48 = 192 measures), the whole piece takes 4 × 96 s = 6:24. To fit 64 bars of 4/4 into 2 minutes you need 256 × 60 ÷ 120 = 128 BPM.
How tempo changes duration (32 bars of 4/4)
| Tempo | Duration |
|---|---|
| 60 BPM | 2:08 |
| 72 BPM | 1:47 |
| 80 BPM | 1:36 |
| 90 BPM | 1:25 |
| 100 BPM | 1:17 |
| 110 BPM | 1:10 |
| 120 BPM | 1:04 |
| 128 BPM | 1:00 |
| 140 BPM | 0:55 |
| 160 BPM | 0:48 |
Inputs explained
| Field | What to enter |
|---|---|
| Calculate | Choose one: Duration from the tempo, Tempo needed for a target duration |
| Time signature | Choose one: 2/2 (cut time), 2/4, 3/4, 4/4 (common time) … |
| Beats per measure | A number |
| Tempo counts | Choose one: The note in the lower number (quarter in 4/4, eighth in 6/8), Dotted beats in compound time (6/8 in 2, 12/8 in 4) |
| Tempo | In BPM |
| Number of measures (per staff) | A number |
| Number of staves / repeats of this length | A number |
| Target duration | Units: min, s, h |
What each result means
- Total beats = [Beats per measure (counted)]×[Number of measures (per staff)]×[Number of staves ÷ repeats of this length]
- Total duration (m:ss) = [Total beats]×60÷[Tempo used]
- Total duration in seconds = [Total beats]×60÷[Tempo used]
- Total duration in minutes = [Total beats]÷[Tempo used]
- Duration of one staff = [Beats per measure (counted)]×[Number of measures (per staff)]×60÷[Tempo used]
- Seconds per measure = [Beats per measure (counted)]×60÷[Tempo used]
- Tempo needed for the target = [Total beats]×60÷[Target duration]
Formula
Beats = beats per measure × measures × staves
Duration (min) = beats ÷ BPM · duration (s) = beats × 60 ÷ BPM
Required tempo = beats × 60 ÷ target duration (s)
Worked example
Inputs — Calculate: Duration from the tempo; Time signature: 4/4 (common time); Tempo counts: The note in the lower number (quarter in 4/4, eighth in 6/8); Tempo: 120 BPM; Number of measures (per staff): 32; Number of staves / repeats of this length: 1.
Results — Beats per measure (counted) = 4; Total beats = 128; Tempo used = 120 BPM; Total duration (m:ss) = 1:04; Total duration in seconds = 64 s; Total duration in minutes = 1.067 min; Duration of one staff = 1:04; Seconds per measure = 2 s.
Key terms
- Measure (bar)
- A segment of music containing the number of beats given by the time signature.
- Tempo
- Speed of the beat, in beats per minute.
- Compound time
- Meters such as 6/8 and 12/8 whose beats divide into three.
- Staff (system)
- One line of music; here a block of measures of equal length.
Frequently asked questions
How long is 32 bars of 4/4 at 120 BPM?
32 × 4 = 128 beats; 128 ÷ 120 = 1.067 min = 1:04.
How do I calculate the length of a song from BPM?
Duration (min) = beats per measure × number of measures ÷ BPM, assuming a steady tempo.
How long is a 3/4 piece of 48 bars at 90 BPM?
144 beats ÷ 90 = 1.6 min = 1:36.
What tempo makes 64 bars of 4/4 last exactly 2 minutes?
256 beats ÷ 2 min = 128 BPM.
How do I count 6/8 at a dotted-quarter tempo?
Choose “dotted beats”: each bar then has 2 beats. 6/8 at ♩. = 60 means one bar per second.
Are repeats included?
No – count repeated sections again or increase the number of staves.
Why does my recording last longer?
Ritardandos, fermatas, pauses between movements and rubato add time that a constant-tempo formula cannot see.