Takt is the German word for the baton a conductor uses to set an orchestra's tempo — and that's exactly what Takt time is for a process: the pace at which one unit must be completed to exactly match customer demand. Miss it in either direction and something breaks — go slower and orders back up, go faster and you're building inventory nobody asked for yet.
The formula
Takt time = available working time ÷ customer demand, both measured over the same period (a shift, a day, a week). Available time is net of breaks, planned maintenance and anything else that isn't production — not the full clock. Eight hours minus a 30-minute lunch and two 10-minute breaks leaves 420 minutes; divide that by however many units the customer needs in a shift, and that's Takt.
Takt time is not cycle time
This trips up almost everyone the first time. Takt time is set by the customer — it's a target, not a measurement. Cycle time (C/T) is what a process actually takes, measured with a stopwatch. The entire point of comparing them is that they're usually different: a process whose C/T is slower than Takt cannot keep up with demand as designed, full stop — no amount of expediting fixes a structurally-too-slow step.
Why the above-Takt flag matters
Once you know Takt, the single most useful thing a value stream map can do is flag every process whose C/T exceeds it — in red, immediately, without you having to do the comparison by hand for every box. That's the diagnostic PruneChart runs automatically the moment you set a Takt time: any process slower than Takt gets a red border and a warning badge, because it's the #1 place waste is costing you throughput.
What to actually do about it
A process running above Takt has three levers, roughly in order of cost: reduce the work content (eliminate motion, combine steps), add capacity (a second operator or machine in parallel), or — the expensive last resort — accept a bottleneck and buffer around it with inventory. What you should never do is silently let it slide; a bottleneck upstream just moves the problem downstream and hides it in a growing queue.
Recalculating Takt
Demand changes, so Takt should get recalculated whenever it does — a seasonal spike, a new customer, a shift pattern change. A future-state map with an old Takt time is quietly wrong; PruneChart's Takt Calculator supports per-shift, weekly and batch-production modes (with unit selection in seconds, minutes or hours) precisely so recalculating doesn't mean redoing the arithmetic by hand.