Lead time calculations
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Summary of Lead time calculations
Lead time in ServiceNow purchasing represents the total days required to fulfill a purchase order for a supplier product. It includes durations for supplier onboarding, sourcing, purchasing, and shipping. These calculated lead times assist customers in planning and managing procurement timelines effectively.
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Supplier Onboarding Time
This is the average number of days to onboard a new supplier for a product or category, with an initial default of 15 days (configurable in purchasing properties). It updates automatically based on actual onboarding task durations from completed purchase requisitions. The onboarding time is calculated by averaging the durations of these tasks per product category and always rounds up decimals.
Sourcing Time
Sourcing time indicates the average days taken to source a product from a supplier, with an initial default of 3 days. It updates as sourcing requests complete for supplier products, product models, and categories by averaging actual durations. New models and supplier products inherit sourcing times from their referenced categories or models. Note that if product categories are marked as Not Addressable, sourcing time is zero, and canceled purchase lines do not affect the average.
Purchasing Time
Purchasing time represents the average days to complete the purchase requisition workflow and generate purchase orders, initially set to 5 days. It updates based on completed purchase requisitions for supplier products, averaging actual durations by supplier product, then by product model, and finally by product category. Blanket order types do not impact purchasing time updates.
Shipping Time
Shipping time estimates the days needed to ship a supplier product to the delivery location. It reflects the shipping time of the associated supplier. Updates to a supplier’s shipping time propagate to all their products. For products created via third-party integration, shipping time is sourced from integration data. Service-type products always have a shipping time of zero.
Total Lead Time Calculation
Total lead time aggregates all relevant durations to reflect the full procurement cycle. The formula varies depending on whether sourcing and supplier onboarding are required:
- If both sourcing and onboarding are needed: Total lead time = Onboarding time (from product category) + Sourcing time + Purchasing time + Shipping time
- If only sourcing is required: Total lead time = Sourcing time + Purchasing time + Shipping time
- If only onboarding is required: Total lead time = Onboarding time + Purchasing time + Shipping time
- If neither is required: Total lead time = Purchasing time + Shipping time
The total lead time recalculates automatically whenever related values on the supplier product are updated and refreshes after each purchase requisition completion based on the last 12 months of data.
Lead time (in days) of a supplier product consist of the time for sourcing, supplier onboarding, purchasing, and shipping for a supplier product, product model, or a product category. Each of these durations are used to calculate the total lead time which determines the number of days to execute a purchase order.
Supplier onboarding time
Supplier onboarding time indicated the average number of days to onboard a new supplier for a product of a category. The initial default value is 15 days, as defined in the sn_shop.default.supplier.onboard.time property of the purchasing properties table.
When a purchase requisition is created for a supplier product, it can have a purchasing task of type supplier onboarding. Over time, as purchase requisitions are completed, the onboarding time for a supplier is updated automatically as follows:
For a product category: Supplier onboarding time = Sum [Actual Duration of supplier tasks for purchase requisitions with purchase lines in a category]/Number of Supplier onboarding tasks.
| Purchase Requisition A for Supplier A | Purchase Requisition B for Supplier B | Purchase Requisition C for Supplier C |
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| Calculated supplier onboarding time in days | ||
Note: If the calculation produces a decimal, always round up regardless of the
value. |
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Sourcing time
Sourcing time indicates the average number of days taken to source a product from a supplier, if sourcing is required for products of a category.
The initial default value is three days, as defined in the sn_shop.default.sourcing.time property of the purchasing properties table. This value is updated over time, as sourcing requests for a supplier product are completed.
- The actual duration values of all sourcing requests for supplier products are considered. An average of these values is calculated. This average is the new default sourcing time for this supplier product.
- When the sourcing time is updated for a supplier product, it is recalculated for the related product model as an average of the sourcing times of all its supplier products.
- When the sourcing time is updated for a product model, it is recalculated for the related product category as an average of the sourcing times of all its product models.
For any new product model, the sourcing time is the same as its referenced model category. For any new supplier product, the sourcing time is the same as its referenced product model.
- If Spend categorization of a product category is Not Addressable, the sourcing time is always 0.
- If the Purchase Line is of the state Closed Canceled, it indicates that sourcing did not occur for that purchase line. In this case, the average sourcing time of the supplier product is not updated.
Example calculation of sourcing time:
| Sourcing Request A for MacBooks | ||
| Actual duration = 16 days | ||
Purchase line 1 – Reseller A MacBook
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Purchase Line 2 – Reseller B MacBook
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Purchase Line 3 – Apple MacBook (assume current sourcing time is 11 days)
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| Sourcing Request B for Lenovo Think Pads | ||
| Actual duration = 22 days | ||
Purchase line 4 – Reseller A Lenovo Think Pad
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Purchase Line 5 – Reseller B Think Pad
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| Calculated sourcing time in days | ||
Note: If the calculation produces a decimal, always round up regardless of the
value. |
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Purchasing time
Purchasing time indicates the average number of days taken to complete the purchase requisition workflow and create purchase orders for products in a category.
The initial default value is five days, as defined in the sn_shop.default.purchasing.time property of the purchasing properties table. This value is updated over time, as purchase requisitions for a supplier product are completed.
- The actual duration values to complete all purchase requisitions for supplier products are considered. An average of these values is calculated. This average is the new default purchasing time for this supplier product.
- When the purchasing time is updated for a supplier product, it is recalculated for the related product model as an average of the purchasing times of all its supplier products.
- When the purchasing time is updated for a product model, it is recalculated for the related product category as an average of the purchasing times of all its product models.
| Purchase Requisition A for Reseller A | Purchase Requisition B for Reseller B | Purchase Requisition C for Reseller B | Purchase Requisition D for Reseller A |
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| Calculated purchasing time in days | |||
Note: If the calculation produces a decimal, always round up regardless of the
value. |
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Shipping time
Shipping time indicates the estimated number of days taken to ship a supplier product to a delivery location. This value is retrieved from the shipping time of a supplier.
Whenever the shipping time for a supplier is updated, the shipping times of all the supplier products belonging to that supplier reflect the same.
Total lead time
Total lead time indicates the numbers of days taken to execute the purchase order of a supplier product and deliver it to the employee.
- If sourcing and supplier onboarding are required,
Total lead time = [Supplier onboarding time from the referenced product category] + [Sourcing time of the supplier product] + [Purchasing time for the supplier product] + [Shipping time of the supplier product].
- If sourcing is required but supplier onboarding is not required,
Total lead time = [Sourcing time of the supplier product] + [Purchasing time for the supplier product] + [Shipping time of the supplier product].
- If sourcing is not required and supplier onboarding is required,
Total lead time = [Supplier onboarding time from the referenced product category] + [Purchasing time for the supplier product] + [Shipping time of the supplier product].
- If sourcing and supplier onboarding are not required,
Total lead time = [Purchasing time for the supplier product] + [Shipping time of the supplier product].
The total lead time of a supplier product is recalculated every time the values of the above fields on the supplier product form are updated.