BizStats (powered by Bizminer)
Financial Calculators – input your own data in the Financial Ratios calculator. Additional calculators available on the site for profit & loss, balance sheet and startup costs (click on All financial calculators link).
Financial Ratio Glossary
Investopedia
Financial ratios – scroll down to Explore Financial Ratios
U.S. Census Bureau
Economic Census - Concentration ratios from the US Economic Census classifies industries by percent of output accounted for by the largest 4,8,20, and 50 companies.
Quarterly Financial Report - quarterly aggregate statistics on the financial results and position of U.S. corporations. QFR presents estimated statements of income and retained earnings, balance sheets, and related financial and operating ratios. For detailed ratios, please use the QFR Financial Data Tables.
WallStreetMojo
Financial ratios – offers a list of top 28 financial ratios with formulas and types