It is possible to do MRP scheduling using spreadsheets. One such system is Resource Manager from User Solutions, South Lyon, MI. It includes a collection of spreadsheet templates that perform the production planning tasks of bill-of-material creation, purchasing requirements planning, job cost justification. This kind of solution is appropriate for small companies with spreadsheet experience and limited resources. It can be used as an interim system prior to adopting a more full featured MRP system

One way to use the system is to schedule individual jobs and plan purchase requirements based on user specified on-hand inventory. A bill-of-material is maintained for each job. The user will specify normal MRP inputs of job and product number, due date, manufacturing lead time, job quantity, bill of material, and component lead times. The bills-of-material are processed to identify net requirements. Capacity information can be obtained by including key machines as components of the bills-of-materials.

The spreadsheet templates support building new data sets. Macros are used to perform the calculations.

Production information needs to be fed back into the spreadsheet prior to the next run. This means that at the beginning of each session, stock inventory, WIP inventory, and purchase order data must be updated.

Resource Manager is a good way to get some basic production and inventory planning information. While it is not a complete, integrated system, the output is generally reliable and useful. It would provide the benefit to small organizations with relatively few end items, or in a make-to-order environment where on-hand inventories are minimal.

Perhaps the biggest benefit of a system like this is that it is an inexpensive introduction to the concept of MRP. It requires the user to organize bills-of-material, inventory records, and planning information such as safety stocks, lead times and component costs. This knowledge should provide companies with a good foundation so as they grow and have more resources, they can easily adapt to larger and more comprehensive systems.