If the business you are buying includes business assets such as furniture or office equipment, you must pay sales tax on them. Here is a quick guide to a few standard business valuation methods.The Interactive Business Valuation Calculator can provide you with a rough idea of the value of your business. This business evaluation calculator uses your current operating profit, expected annual growth, and the length of time you expect to grow at this rate. A valuation formula is used to determine what is the company worth. Here are 10 best calculations to help your business valuation. Want to know how to calculate business valuation? Now it's time to agree on a purchase price. Here's how to calculate a company valuation so you can negotiate with confidence.