Bars and Song Length
How long an arrangement runs, and how many bars fit a target duration. Works in any time signature.
Beats per minute, 20 to 400.
Or set a duration below to work backwards.
Type a duration to get the bar count.
One bar lasts 2000 ms at 120 BPM.
- Per beat
- ms
- Per bar (4/4)
- ms
- Frequency
- Hz
- 1/8 delay
- ms
One bar of 4/4 at 128 BPM lasts 1.875 seconds, so a 96-bar arrangement runs three minutes exactly. Enter a bar count for the duration, or a target duration to get the bar count. Odd time signatures are handled by scaling the bar to its quarter-note length.
Common bar counts at this tempo
Arrangements move in fours, eights and sixteens because phrases resolve on those boundaries. These are the durations you are actually working with.
| Bars | Duration | Seconds | Typically |
|---|---|---|---|
| 4 | 0:08 | 8 | A short fill, turnaround or one-line hook. |
| 8 | 0:16 | 16 | A verse half, or a full intro. |
| 16 | 0:32 | 32 | A standard verse or chorus. |
| 32 | 1:04 | 64 | Verse plus chorus, or a full club intro. |
| 64 | 2:08 | 128 | Roughly half a radio edit. |
| 96 | 3:12 | 192 | A complete short arrangement. |
| 128 | 4:16 | 256 | A full club arrangement with room to breathe. |
The maths
bar length = (60000 ÷ BPM) × beats × (4 ÷ note value)
A BPM beat is a quarter note. A bar of 4/4 holds four of them, so at 120 BPM it lasts 2000 ms. Multiply by the bar count for the total.
Odd signatures work the same way once you convert to quarter-note beats. A 6/8 bar holds six eighth notes, which is three quarter notes, so it runs three quarter-note beats long — not six.
Why arrangements land on round numbers
At 128 BPM, sixteen bars is thirty seconds almost exactly. That is not a coincidence so much as a convenience the genre grew into: 96 bars gives you three minutes, 128 bars gives you four. Producers pick tempos partly because the arithmetic falls out cleanly.
If you are writing to a fixed duration — a sync brief, a radio edit, a 30-second spot — work backwards. Enter the target above and the tool gives you the bar count, which is the number you actually arrange to.
Bar one is bar one, not bar zero. Most DAWs number the first bar as 1, so a 16-bar section starting at bar 1 ends at the start of bar 17. Off-by-one errors here are the usual cause of a section landing a bar early.
Need every value at once?
The main BPM calculator shows milliseconds, delay times, reverb ranges, hertz and bar length together, updating from a single tempo.
Counting bars and song structure
Why phrases group in eights, how to map a structure onto a duration, and where bar counts come from in a DAW.
Common questions
How long is 16 bars at 128 BPM?
Thirty seconds exactly. A bar of 4/4 at 128 BPM lasts 1.875 seconds, so sixteen of them come to 30 seconds. That is a large part of why 128 became a default club tempo.
How many bars are in a three-minute song?
At 128 BPM in 4/4, 96 bars. At 120 BPM, 90 bars. At 174 BPM, 130 bars. Enter a target duration above and the tool gives you the bar count.
How does this work in 6/8 or 7/8?
A bar is converted to its quarter-note length first. A 6/8 bar holds six eighth notes, which is three quarter notes, so it runs three beats long rather than six.
Related tools and guides
- Online Metronome A sample-accurate metronome with time signatures, accented downbeats and subdivisions. Runs in the browser with no download and no sign-up. Tool
- BPM Calculator Tap a tempo and get every value it drives: milliseconds per beat, delay and reverb times, hertz, frames and bar length. Free, instant, no sign-up.
- Tempo Change Calculator Work out half-time and double-time tempos, percentage changes and the difference between two tempos, with the effect on beat length shown. Converter
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