LambResearch  

Although this database is based on public companies, it is included in the private company section because of its utility in estimating a company's value based on its sales.  Aswath Damodaran at NYU Stern has done a great service to the prospect research community by compiling this list of ratios based on public company reports.  This can be used for estimating private company value based on sales by industry.  Look for the EV:Sales ratio.  EV as in “enterprise value”.  Find the industry that your target company is part of, then multiply its reported annual sales by the EV:Sales ratio to estimate company value.  Note that the ratios include international corporations.  Also be aware that, since these ratios are based on public companies, those companies will usually be somewhat more valuable than an otherwise equivalent private company.  Thanks Aswath!