Hi ​@sboyd ,

The unit of measure for both purchasing lead time and supplier manufacturing lead time is Days.

Below passage from IFS Documentation provides further insights into types of days.

“

Total Purchase Lead Time

The total lead time of a purchase part is the time from when the part is ordered until it is available in inventory. The total purchase lead time is normally calculated in the Calculate Purchase Lead Time assistant by using the following four elements:

• Supplier Manufacturing Lead Time: The time from recognition of need for replenishment at the supplier until the product is ready for shipment from the supplier. This could be a replenishment either via manufacturing or via purchasing. The manufacturing lead time is measured in supplier calendar days, which only includes workdays. If no supplier calendar is defined, manufacturing lead time is measured in calendar days, which includes weekends and holidays. The information is retrieved from the combination of supplier and purchase part.
• External Service Lead Time: The time taken by the external supplier to perform any service or repair work after the product is delivered to the supplier. This is applicable only when external service order is used. The external service lead time is measured in supplier calendar days, which only includes workdays. If no supplier calendar is defined, this lead time is measured in calendar days, which includes weekends and holidays. The information is retrieved from the combination of supplier, purchase part and external service type.
• External Transport Lead Time: The transportation time from a supply node to a demand node during which the supplying party has the responsibility. The external transport lead time is measured in external transport calendar days, which only includes workdays. If no external transport calendar is defined, external transport lead time is measured in calendar days, which includes weekends and holidays. The external transport calendar is defined by the ship via code. The information is retrieved from supply chain parameters.
• Transport Lead Time: The transportation time from the delivery point of a supply node to a demand node during which the demanding party has the responsibility.  This can be in cases where, for instance, a supplier has the delivery point some distance away from your company. Consequently, you must take the responsibility to transport the goods from that delivery point to your receiving point. The transport lead time is measured in external transport calendar days, which only includes workdays. The information is retrieved from supply chain parameters.
• Internal Transport Lead Time: The lead time from the receiving point to the inspection point or to the shop floor. This may include administration time, queuing time and transportation time after the receiving point and before the inspection point or shop floor.  The internal transport lead time is measured in site distribution calendar days, which only includes workdays. The information is retrieved from supply chain parameters.
• Internal Inspection Lead Time: The time it takes to inspect the goods, after which they are available in inventory. In other words, the time it takes from when the part is available for inspection until the part is available in inventory. During this time, activities such as inspection, quarantine, and other activities that delay the part from reaching inventory can occur. The internal inspection lead time is measured in site distribution calendar days, which only includes work days. The information is retrieved from the combination of supplier and purchase part.

When you specify the Update option when calculating the total purchase lead time, the result is presented in the inventory part record.

If the calculate purchase lead time function is not used, the default value will be set to 0 (zero). However, it is also possible to manually enter a value in the inventory part record.

The total purchase lead time is used for calculating dates when entering purchase requisitions or purchase orders.”

You may refer below IFS Documentation link to read more on Lead Times used in IFS Cloud.

https://docs.ifs.com/ifsclouddocs/25r1/MaintainInventory/AboutLeadTime.htm#Total%20Purchase%20Lead%20Time?StandAlone=true

Regards,
Kethaka