Loop Length Calculator
Convert a musical loop length in bars into its duration in seconds at any tempo. Use it when programming drum machines, DAWs, or live sets where loop timing must sync with BPM.
About this calculator
A loop's duration in seconds depends on how many bars it contains, the number of beats per bar, and the tempo in beats per minute. The formula is: Loop Length (s) = (Bars × Beats Per Bar × 60) / BPM. Here, Bars × Beats Per Bar gives the total number of beats in the loop, and multiplying by 60 converts the BPM denominator from minutes to seconds. For a standard 4/4 loop at 120 BPM, one bar lasts exactly 2 seconds and four bars last 8 seconds. Knowing the exact loop length in seconds is essential for setting buffer sizes, configuring hardware loopers, aligning video to audio, or ensuring seamless playback in Ableton Live, Logic Pro, or any sample-based workflow.
How to use
You are building an 8-bar drum loop at 90 BPM in 4/4 time. Enter 8 in Loop Length (Bars), 90 in Tempo (BPM), and 4 in Beats Per Bar. The formula evaluates: (8 × 4 × 60) / 90 = 1920 / 90 ≈ 21.33 seconds. Your loop is approximately 21.33 seconds long. If you later change the tempo to 120 BPM, re-enter 120 and the result becomes (8 × 4 × 60) / 120 = 16 seconds — a useful check when resampling loops for different projects.
Frequently asked questions
How do I calculate loop length in samples instead of seconds?
Multiply the loop length in seconds by the sample rate of your project. For example, a 16-second loop at a 44100 Hz sample rate spans 16 × 44100 = 705,600 samples. This sample count is what your DAW or hardware looper stores internally and is critical when exporting loops that must be perfectly seamless. Even a single sample of error at a loop boundary can introduce a click or a timing glitch audible after many repetitions.
Why does changing BPM affect how long a loop sounds but not its musical content?
Tempo defines how many beats occur per minute, so the same number of bars takes more clock time at a lower BPM and less time at a higher BPM. The musical content — the notes, chords, and rhythmic patterns — is defined relative to the beat grid, not absolute time. When you stretch or compress a loop to a new BPM in a DAW using time-stretching, the pitch is preserved but transients may soften. When you change tempo without time-stretching, the loop plays at a different speed and its pitch shifts proportionally.
What is the standard number of beats per bar for common music genres?
Most electronic music, pop, rock, and hip-hop use 4/4 time, meaning 4 beats per bar — the default for this calculator. Waltz and some folk music uses 3/4 time (3 beats per bar), while genres like progressive rock occasionally use 5/4, 7/8, or other irregular meters. Afrobeat and some jazz styles use 6/8, which is often counted as 2 beats per bar of compound time. Entering the correct beats-per-bar value is important: a 4-bar loop in 3/4 at 120 BPM lasts 6 seconds, whereas the same loop in 4/4 lasts 8 seconds.