About this tool
Work out how long an arrangement runs or how many bars you need to fill a slot, converting freely in both directions. Pick a mode, enter the tempo and beats per bar, then either a bar count or a target duration — all in your browser with nothing uploaded.
The core relationship is duration (seconds) = bars × beatsPerBar × (60 ÷ BPM); one bar lasts beatsPerBar × (60 ÷ BPM) seconds. Reversed, bars = duration ÷ (beatsPerBar × 60 ÷ BPM). For example 32 bars of 4/4 at 120 BPM run 32 × 4 × 0.5 = 64 seconds, or 1:04, and 128 total beats. Time-from-bars mode prints the length as mm:ss plus raw seconds and total beats; bars-from-time mode prints the bar count (which can be fractional) and total beats.
This is ideal for arrangers, film and game composers, and producers building loops — set the tempo, then read off exactly how many bars fill a scene or how long your section will play. Results recalculate live as you edit any field.