BPM & bar-length calculator

Calculate beat and bar lengths at a constant tempo in 4/4.

Formula

One beat (seconds) = 60 ÷ BPM
N bars in 4/4 (seconds) = 240 × N ÷ BPM

Four bars last 8 seconds at 120 BPM, 9.6 seconds at 100 BPM and about 6.8571 seconds at 140 BPM.