Queue, setup, touch time, waiting, and rework flowing through an expedite sluiceUpdates with every input
Date & Time
Lead Time Duration Calculator
Decompose end-to-end lead time into queue, setup, batch processing, inter-batch waiting, defect rework, and expedite compression instead of treating all elapsed time as touch time.
Base processing touch time—
Number of batches—
Total setup time—
Inter-batch waiting—
Expected rework time—
Standard lead time—
Time saved by expediting—
Expedited lead time—
Elapsed-time river
Queue, setup, touch time, waiting, and rework flowing through an expedite sluice
The river width represents hours in each lead-time source; a compression bracket shows exactly which delays expediting can reduce.
Batch passage ledger
Lead-time accumulation by production batch
See setup, unit processing, expected rework, inter-batch wait, cumulative standard time, and expedited cumulative time.
| Batch | Units | Setup | Touch time | Rework | Following wait | Cumulative standard | Cumulative expedited |
|---|
Lead-time setup
Measure elapsed delays separately from processing effort
- Enter queue time before the first batch.
- Count every repeated setup.
- Use physical processing time per unit.
- Add waits only between batches.
- Apply expediting only to controllable delay.
Flow-time logic
Lead time grows through repeated gates, not just unit quantity
Smaller batches can improve flow but repeat setup more often; larger batches reduce setup count while creating longer accumulation intervals.
Expediting cannot make the physical process disappear, so the model compresses queue and waits only.
Calculation method
Separate value-adding touch time from queue and transfer delays
Batch count drives repeated setups and waits. Expected defects add repeat processing. Expediting reduces only queue and inter-batch waiting, not physical touch or rework.
Detailed calculation process and general formulas
B=ceil(Q/q)T_touch=QpT_setup=BsT_rework=QrpT_net=T_touch+T_setup+T_rework+(T_queue+T_wait)(1-e)Symbols, meanings, and units
- Q
- order quantityunits
- q
- batch sizeunits/batch
- p
- processing time per unithours/unit
- r
- expected rework sharedecimal
- e
- queue and wait reductiondecimal
Delay anatomy
Find the part of lead time worth attacking
The decomposition distinguishes customer-visible elapsed time from labor-bearing processing and quality loss.
Touch work
—Base physical processing time.
Batch overhead
—Repeated setup across all batches.
Quality loss
—Expected repeat processing.
Expedite value
—Queue and wait time removed.
Decision takeaway: Improve the largest controllable delay source; paying to expedite a touch-time-dominated order produces little benefit.
Flow checks
Validate what repeats and what does not
- Some setup time can overlap queue release.
- Defects may require more than one rework pass.
- Waits can vary by batch.
- Expedite policies may increase setup or handling risk.
Lead-time evidence
Operational records that calibrate the model
- Queue timestamps
- Setup logs
- Cycle-time observations
- Batch transfer timestamps
- Defect and rework records
Practical applications
Decisions this calculator is designed to support
Fabrication order
A custom order moves in four lots with setup and inspection waits.
What the result clarifies: The river shows whether batching or touch time controls delivery.
Expedited laboratory queue
Priority handling can reduce waiting but not test duration.
What the result clarifies: The compression bracket prevents overstating the benefit of expediting.
Worked example
Current-input substitution and reconciliation
Model limitations
This expected-value model assumes uniform units, one rework pass, constant batch size, and identical waits. It excludes resource contention, parallel machines, transport calendars, and stochastic queue distributions.
Lead Time Duration Calculator FAQ
Why does setup repeat?
The entered setup time is applied once to every production batch.
Is wait added after the final batch?
No. Inter-batch wait occurs only between batches.
What does expediting reduce?
Only initial queue and inter-batch waiting.
How is rework estimated?
Expected defective units are multiplied by the original per-unit process time.