I'd like a little help with creating a Inventory Budget. Some of my internet searches have lead me to the concept of OTB open to buy. This OTB takes into consideration Beginning Inventory, Sales Targets, Purchases, etc. I have a spreadsheet created but I'm having a little trouble with the logic. Does anyone have any experience with this subject?

The most important factor for an inventory budget is the sale forecast/projection. Actually almost all budget start with Sales level.

When you know what the expected sales are, you can use the simple math for inventory by using beginning, purchase, etc.