It really depends on the stage of your business. For example, if your business has been around for a while or has reached a "normalized" level of profitability, the most common valuation approach would be to apply a multiple to EBITDA (earnings before interest, tax, depreciation, and amortization) - i.e., if your business produced annual EBITDA of $100, and you are in an industry where publicly traded companies generally trade for 10x EBITDA, your business would have a value of $1,000 ($100 x 10).
For a company that is generating sales, but either has not reached profitability or has not reached "normalized" profitability, you would generally apply a revenue multiple (i.e., total annual sales of $500, and companies generally trade for 2x revenue, so you'd assume $500 x 2 to get to a value of $1,000).
The other approach for a newer stage venture, as folks highlighted before, would be based on a discounted cash flow model, which is where you essentially estimate what your future sales, expenses, and profitability will be, and use that to imply the value of the business today. The problem with this approach is that it is incredibly subjective, and there will likely be disagreements between investors and entrepreneurs on the risks associated with the forecast you prepare. There are a few ways to get around that with investors (e.g., preferred share structures to reduce the investor's risk by prioritizing their equity holding, earn-outs, etc.).
In terms of an online tool, I'm assuming each would use one of the approaches above, just depends on which is most appropriate for your business.
Publié le 13/08/18