Calculate procurement, production, shipping, or total supply-chain lead time in calendar or business days. Buyers, planners, manufacturers, and logistics teams can estimate a delivery date, set a planning buffer, find the bottleneck, compare a target scenario, and optionally calculate replenishment dates.
Duplicate the current plan, then change a supplier, process, or transport assumption.
Map the full interval from trigger to usable receipt: sourcing, approvals, queues, production, inspection, packaging, transport, customs or port handling, last mile, receiving, and installation where relevant.
Prefer actual purchase orders and receipt history. Reconcile those records with supplier commitments, production schedules, carrier transit promises, customs records, and receiving timestamps.
Do not mix hours, working days, and calendar days without conversion; omit queue or receiving time; count the start date inconsistently; or treat a quoted transit duration as total supplier lead time.
Start with the largest percentage. Test supplier capacity, approval queues, batch sizes, shipping mode, customs documentation, receiving appointments, or installation readiness—then compare the change as a target scenario.
| Measure | What it measures | Typical boundary |
|---|---|---|
| Lead time | Total elapsed wait plus work | Request/order to usable receipt |
| Cycle time | Time to complete one process cycle | Work start to work completion |
| Processing time | Time actively worked | Hands-on or machine activity only |
| Transit time | Movement between locations | Carrier pickup to delivery |
| Takt time | Required production pace | Available production time ÷ customer demand |
Use one consistent unit before applying these formulas. This calculator converts hours ÷ 24 and weeks × 7 to days.
L = S₁ + S₂ + … + Sₙ, where S is each stage duration and n is the stage count.L = receipt date − order date, counted consistently as calendar or working days.L̄ = ΣLᵢ ÷ m, where m is the number of comparable historical orders.P = L + B, with day buffer B; or P = L × (1 + b/100) for percentage buffer b.Dᴸ = d × P, where d is average daily demand. Reorder point: ROP = Dᴸ + SS, where SS is safety stock.Sₓ = target L − sum of known stages.production max = available counted days − all other stages − buffer.Calendar arithmetic counts every date. Working-day arithmetic skips Saturdays, Sundays, and valid holiday exclusions. The result follows the selected start-date counting rule.
Approval 2 + sourcing 4 + production 12 + port handling 3 + ocean transit 18 + customs 4 + last mile 2 + receiving 1 = 46 calendar days. Ocean transit is the 39.1% bottleneck. From 1 August with a 10% buffer (4.6 days), the plan rounds to a 51-day delivery date; the buying decision is to order at least 51 calendar days before need.
Approval 1 + supplier processing 2 + production 5 + ground transit 2 + receiving 1 = 11 business days. Production is 45.5%. Starting Monday 6 July and counting it as day one gives Monday 20 July; review capacity if that date misses the requirement.
Queue 3 + setup 0.5 + processing 2 + inspection 1 + packaging 0.5 = 7 days. Queue time is 42.9%, so smaller release batches or scheduling changes deserve the first test.
A required receipt in 20 business days, with 3 approval days, 4 transit days, 1 receiving day, and a 2-day buffer, leaves 20 − 3 − 4 − 1 − 2 = 10 business days as the maximum allowable production time.
Editorial owner: Starlight Robotics Editorial Team · Reviewed: 18 July 2026
The calculator sums sequential stages after converting them to days, applies a transparent day or percentage buffer, then advances the selected start date using the chosen counting convention. Weekends and entered holidays are excluded only in business-day mode. Fractional durations are retained in totals; delivery dates represent the date on which the final fractional day falls.
Results assume stages are sequential rather than overlapping, 24 hours per day, seven days per week, and Monday–Friday business weeks. They do not model cutoff times, shifts, time zones, carrier-specific calendars, parallel work, or probability distributions. Source inputs from purchase orders, supplier commitments, carriers, and actual receipt history; use like-for-like historical orders.
Calendar-day lead time advances through every date. Business-day lead time counts Monday through Friday and skips entered holidays, so the same duration usually produces a later delivery date.
Weekends count in calendar-day mode. In business-day mode, Saturdays and Sundays are excluded automatically. Select the mode that matches the supplier or carrier commitment.
Enter holiday dates as comma-separated ISO dates. The calculator excludes those dates in business-day mode only; calendar-day schedules still count them.
Lead time measures elapsed time from request or order to availability and can include queues and transport. Cycle time measures the time required to complete one process cycle after work begins.
Supplier lead time covers the period from purchase order to receipt. Manufacturing lead time covers queue, setup, processing, inspection, and movement needed to produce an item internally.
For each comparable order, subtract its order date from its receipt date using one consistent day convention, add the observed lead times, and divide by the number of orders. Keep minimum and maximum values to show variability.
Include every interval between the planning trigger and usable receipt, including sourcing, approvals, queues, production, inspection, packaging, transport, customs or port handling, last mile, receiving, and installation when applicable. Use zero for stages that do not apply.
Base the buffer on actual supplier and receipt variation, service risk, and review cadence. A percentage or day buffer is a planning allowance, not a statistically calculated safety-stock quantity.
Lead-time demand equals average daily demand multiplied by planning lead time. Adding safety stock gives the reorder point, so longer planning lead time generally triggers replenishment earlier.
Choose a start date and add planning lead-time days using calendar or business-day arithmetic. If the start counts as day one, the calculator advances one fewer counted day; otherwise counting begins after the start date.
This is a transparent planning estimate, not a supplier guarantee or safety-stock model. Validate critical purchasing and production decisions against current commitments, cutoff times, local calendars, and observed performance.