How to calculate the capital gain for mutual fund?

if it is a taxable retail acct, calculate average cost basis: add up all the contributions, divs reinvested and cap gains (of the fund) reinvested (the values, ie $1000 cont, $50 div, $250 CG = $1300). Now add up the # of shares each addition made ($1000 cont bought 1000 shrs, $50 div bought 40 shrs, $250 CG bought 200 = 1240 shrs). Divide dollars by shares, and you get an avergage cost per shr ($1300/1240 shrs = $1.048/shr). So if you now sold 1000 shrs for $1.25, your cost basis would be $1048, you would get $1250 for the sale, and $202 would be taxable.

divs and CG increase cost basis bc you pay those taxes annually, not when you sell shrs.

For an IRA or other tax deferred, just add up the contributions. Everything above that is considered earnings.

This can be a difficult process if you are reinvesting your dividends because the reinvestments are made at the then current price and over several years it can become very complicated. Your mutual fund company's on line site should be able to answer that question. Sign on to their web site and create a user id and the information should be readily available.

If you are not reinvesting your dividends, the process is simpler. Just take the current share price times the number of shares you own and subtract (hopefully) the share cost.