To create an inventory spreadsheet, open the spreadsheet software of your choice and choose the icon for a new document. Set aside a page for each type of product to be inventoried. Create headers, such as "Product Name," "Cost," "Price" and "Description," in the first row of the columns.
Other headlines needed in the first row per product page are "Date," "Quantity In," "Quantity Out" and "Total On Hand." The next row is where the information of the headings is actually listed about the product. "Date" and "Total On Hand" are good headings to keep close to each other to keep track of the current amount of product for restocking purposes.
"Quantity In" is the amount of the product that was received in that day's shipment. "Quantity Out" records the amount of the product sold for that day. These are important numbers to keep track of supply and demand for certain products and as such are good to place together on the spreadsheet. Check these numbers against the "Total On Hand" calculations. They should be identical once "Quantity Out" is subtracted from "Quantity In" and the amount that was already on hand the day before.
Apply the same information for every product page. When combining products on a single page, be sure to make a clear demarcation between products to avoid confusion or miscalculation. The spreadsheet must be easy to navigate and easy to update or replicate.