Capacity tiles moving toward a customer service-level gateUpdates with every input
Date & Time
Lead Time Business-Day Calculator
Convert a unit requirement into a business-day delivery promise after weekends, holidays, shutdown days, partial-capacity dates, and a customer service-level target.
Productive business days—
Calendar-day lead time—
Finish weekday—
Final-day production—
Excluded calendar days—
Service-level slack—
Scheduled capacity utilization—
Service promise status—
Business-day delivery conveyor
Capacity tiles moving toward a customer service-level gate
Each date tile shows delivered capacity or an exclusion, while a vertical gate marks the service target and the final partial-load tile.
Delivery calendar
Business-day capacity and service-promise ledger
Review date offset, weekday, availability type, scheduled capacity, cumulative output, remaining units, and service-target margin.
| Day | Weekday | Availability | Scheduled capacity | Cumulative output | Remaining units | Target margin |
|---|
Promise setup
Build the promise from actual eligible dates
- Enter the full requirement and sustainable daily capacity.
- Set the starting weekday.
- Count holidays and shutdowns inside the horizon.
- Use the partial-day factor for a known constrained date.
- Compare the finish span with the service target.
Calendar logic
Customer lead time measures elapsed dates, not productive-day count
Nonworking dates are invisible to simple units-per-day division but remain visible to the customer.
The conveyor retains exclusions and the final partial load, giving operations a daily reconciliation path.
Calculation method
Walk the calendar and consume demand only on eligible capacity dates
Weekends, holidays, and shutdowns add elapsed time but no output. One planned partial-capacity day is applied before full production resumes.
Detailed calculation process and general formulas
Cap_t=d for full datesCap_partial=df_pQ_t=min(Cap_t,R_(t-1))R_t=max(R_(t-1)-Q_t,0)Slack=S-SpanSymbols, meanings, and units
- d
- full business-day capacityunits/day
- f_p
- partial-day capacity factordecimal
- Q_t
- units scheduled on date tunits
- R_t
- units remaining after date tunits
- S
- customer service targetcalendar days
Service promise anatomy
Why a technically feasible order can still miss service level
Capacity can be sufficient in productive-day terms while exclusions push elapsed delivery beyond the customer target.
Working requirement
—Business dates that carry production.
Elapsed promise
—All calendar dates through completion.
Service margin
—Target days less projected span.
Last-day load
—Residual units placed on the finish date.
Decision takeaway: Quote the elapsed promise externally and use productive days internally for staffing; combining them hides calendar risk.
Calendar checks
Confirm every exclusion inside the likely span
- Holiday counts should reflect actual dates.
- Shutdowns may overlap weekends.
- Partial capacity may occur on another date.
- Workweek definitions can differ by location.
Promise evidence
Records supporting the delivery commitment
- Production calendar
- Holiday and shutdown notices
- Capacity history
- Customer service-level agreement
- Order completion scan
Practical applications
Decisions this calculator is designed to support
Custom manufacturing promise
An order crosses a holiday and two maintenance shutdown days.
What the result clarifies: The conveyor makes the elapsed delay and service margin explicit.
Laboratory turnaround
A large sample batch includes one partial-capacity calibration day.
What the result clarifies: The final promise uses actual daily availability instead of average capacity.
Worked example
Current-input substitution and reconciliation
Model limitations
The model uses a relative calendar and assigns holidays and shutdowns as early eligible exclusions. It does not resolve named dates, overlapping exclusion categories, multiple partial days, variable capacity, or priority sequencing.
Lead Time Business-Day Calculator FAQ
Why is calendar span longer than productive days?
Weekend, holiday, and shutdown dates add elapsed time without output.
How is the partial day used?
One eligible date receives the entered fraction of full capacity.
What is service-level slack?
Customer target days minus projected calendar span.
Can workweeks contain seven days?
Yes; set workdays per week to seven.