item attributes Standard Lot Size and Lead time lot size

You have key item attributes of Standard Lot Size in Costing tab and Lead time lot size in Lead times tab of Item Master. It is observed that there are many users who do not have clear understanding of these two lot sizes and wonder what is used where. For example, where Standard Lot size used in transactions like a WIP Job Creation or MRP run?

Hence the clarification is provided.

Standard lot size works different depending on setup for Lead time lot size.

When used without any Lead time lot size, the Standard lot size  is used for Costing the item as well as to calculate the Manufacturing lead time. When you want to use different lot size for calculating Manufacturing lead time  you can define the Lead time lot size as well.