How do I amortize setup time per unit?

Divide the setup time for the run by the good units in the batch. A 600-second changeover on a 200-unit batch adds 3 seconds to every unit, and doubling the batch halves that adder.

Where does the minor stop allowance come from?

Time the small interruptions for several shifts and divide the total lost time by the units made. Jams, sensor faults and micro adjustments usually grow with speed, so recheck the allowance after any rate change.

Is the bottleneck always the slowest machine?

Not always: a faster station with long setups or frequent stops can consume more time per unit. The constraint is the operation whose effective cycle limits the output of the line.

Why compare the cycle with takt instead of output?

Takt turns customer demand into seconds per unit, so the constraint is judged against what the line must ship, not against its last good hour. Seconds compare directly with the cycle and show how much has to come out.

Lean Manufacturing & Operations calculator

Bottleneck Cycle Time Calculator

Work out what the constraint really takes per unit once setup and minor stops are counted, then compare that pace with takt. You need base processing time, amortized setup, a stop allowance and takt.

What this calculator does

Effective bottleneck cycle time from processing, setup and stops, with the constraint output rate and its gap to takt.

Formula used

Effective bottleneck cycle = base processing + amortized setup + minor stop allowance
Output rate at bottleneck = 3,600 ÷ effective bottleneck cycle
Setup share of cycle = amortized setup ÷ effective cycle × 100
Gap to takt = takt time − effective bottleneck cycle

Inputs explained

Base Processing Time per Unit: Pure run time per unit at the constraint, from the time study.
Amortized Setup Time per Unit: Changeover time divided by the batch size for this part.
Minor Stop Allowance per Unit: Small stoppages per unit from the downtime log or observation.
Takt Time: Demand pace the constraint must meet, from the sales plan.

How to use the result

Best suited to verifying the suspected constraint, sizing a setup reduction project, checking a quote against the slowest station.
An average stop allowance hides bursty stoppages that cost more than their average share. Base processing time excludes operator pace changes across shifts and crews.

Current U.S. benchmarks

U.S. manufacturing runs at 75.7% of capacity (Federal Reserve, Aug 2026). New factory orders are up 8.5% year over year (Census).

Common questions

How do I amortize setup time per unit? Divide the setup time for the run by the good units in the batch. A 600-second changeover on a 200-unit batch adds 3 seconds to every unit, and doubling the batch halves that adder.
Where does the minor stop allowance come from? Time the small interruptions for several shifts and divide the total lost time by the units made. Jams, sensor faults and micro adjustments usually grow with speed, so recheck the allowance after any rate change.
Is the bottleneck always the slowest machine? Not always: a faster station with long setups or frequent stops can consume more time per unit. The constraint is the operation whose effective cycle limits the output of the line.
Why compare the cycle with takt instead of output? Takt turns customer demand into seconds per unit, so the constraint is judged against what the line must ship, not against its last good hour. Seconds compare directly with the cycle and show how much has to come out.

Last reviewed 2026-10-01.