Free stock calculators that show their maths
Each calculator runs in your browser, shows the formula it uses and includes a worked example you can redo by hand.
Compound growth calculator
See how a starting amount plus monthly additions could grow at an assumed yearly return. Shows the formula, a worked example and what the result leaves out.
Dividend yield calculator
Work out a stock's dividend yield, annual dividend, yearly income on your shares and payout ratio. Shows the formula and a worked example you can check by hand.
Fund fee calculator
Compare two funds' expense ratios and see the dollar difference over time. Shows the formula, a worked example matching the defaults, and its limits.
P/E ratio calculator
Work out a stock's price-to-earnings ratio, its earnings yield and a forward P/E from your own forecast. Shows the formula and a worked example you can check.
Percentage change calculator
Work out the percentage change between two stock prices, the gain needed to get back after a fall, and the yearly rate over several years. Formula shown.
Position size calculator
Work out how many shares to buy from your account size, the most you will lose and your stop price. Shows the formula and a worked example.