🥁 Bar & Time Signature Calculator
Enter the tempo and time signature to get the length of one bar — and of any number of bars — in seconds.
One bar
2 s
16 bars
0:32.0
Bars per minute
30
One bar lasts beats-per-bar × (4 ÷ denominator) × (60 ÷ BPM) seconds. BPM counts quarter-notes, so a bar of 4/4 at 120 BPM is 2 seconds; 6/8 at 120 is 1.5 seconds. Handy for arranging song sections to a target length. 🔒 In your browser.
How the bar & time signature calculator works
BPM counts quarter-notes per minute, so a quarter-note beat is 60 ÷ BPM seconds. One bar lasts beats-per-bar × (4 ÷ denominator) × (60 ÷ BPM) seconds — the (4 ÷ denominator) term adjusts for time signatures whose beat isn't a quarter note. Multiply by the number of bars for a section's total length.
This is handy for arranging: working out how many bars fit a 30-second ad, or how long an 8-bar intro runs. A bar of 4/4 at 120 BPM is 2 seconds; the same tempo in 6/8 gives 1.5-second bars.
Frequently asked questions
How long is one bar of music?
It depends on tempo and time signature: bar = beats-per-bar × (4 ÷ denominator) × (60 ÷ BPM) seconds. A 4/4 bar at 120 BPM is 2 seconds; at 90 BPM it's about 2.67 seconds.
How do I work out how many bars fit in a time?
Divide the target time by the length of one bar. At 120 BPM in 4/4 (2-second bars), a 30-second section is 15 bars. The tool shows bars-per-minute to make this easy.
How does the time signature affect bar length?
The bottom number sets which note gets the beat, and the top sets how many. Since BPM counts quarter-notes, the (4 ÷ denominator) factor accounts for eighth-note or half-note beats — 6/8 bars are shorter than 6/4 at the same BPM.
How long is a 4/4 bar at 120 BPM?
Exactly 2 seconds — four quarter-note beats at 0.5 seconds each (60 ÷ 120). Eight bars would be 16 seconds.
Why calculate bar lengths?
For arranging and syncing: fitting a song section to a video cue, planning an intro of a set length, or lining up loops. Knowing the seconds-per-bar turns musical structure into clock time.