How to Calculate Stock Gain

Compute the cost basis for the stock trade. Cost basis consists of the original (purchase) price of the stock plus all fees and commissions paid for the purchase and sale of the stock. For example, if you bought 100 shares of a stock at $10/share ($1,000) and paid fees of $10 when you bought the stock and $12 to sell it, your cost basis is $1,000 plus $10 plus $12 for a total of $1,022.
Calculate the total proceeds. Your total proceeds include the money received from selling the stock plus the cash value of dividends received while you owned the shares. For instance, if you sold the 100 shares from Step 1 for $15/share ($1,500) and received a total of $50 in dividend income during the time you held the shares, your total proceeds are $1,500 plus $50, or $1,550.
Calculate stock gain or loss. Subtract the cost basis from total proceeds. If your cost basis is $1,022 (Step 1) and total proceeds are $1,550 (Step 2) your stock gain is $1,550 minus $1,022, which equals $528. If you get a negative number (meaning the cost basis is greater than total proceeds) you had a loss rather than a gain.
Figure your percentage gain or loss. It’s usually most useful to compare percentage gain or loss to see how well different investments have done. To convert stock gain into percentage stock gain, divide the stock gain by the cost basis and multiply by 100. In the example above, you would divide $528 (stock gain) by $1,022 (cost basis) and multiply the result by 100 to get a percentage stock gain of 51.7 percent.

How to Calculate Stock Averages

Add the total value of stock purchased on each stock ticket. This should be on your statement or ticket. If you don't have this, take the number of shares and multiply this to the price paid per share. For example, if you purchased 100 shares of XYZ stock at $15 per share, this would be $1500.
Add the total value of each purchase together. Assume you bought XYZ three times, each time purchasing 100 shares. You paid the following prices: $15, $10, $12. You would then have spent: $1500 + $1000 + $1200 = $3700.
Add the total number of shares you have purchased. For example if you bought 100 shares of XYZ stock three times, then you would have 300 shares total.
Divide the total dollar value spent by the total shares purchased: $3700/300 = $12.33/ per share.
You might need to consider the cost per transaction paid. If you are paying a commission for buying the stock, then add the commission price into the total amount spent before dividing it by the total number of shares. If you want to know your break-even price, add the estimated sales commission to the total dollar value as well. For example, if you spent $8 for each of the three trades, then: $3700 + $8 + $8 + $8 = $3724 for the total purchase price. If you will spend $8 on the sale, then your total would be $3732 / 300 shares = $12.44 for your break-even price.

How to Read Stock Prices (6 Steps)

Look up the symbol of the company you are interested in on sites like Yahoo's Finance page, eTrade and MSN Money. Use this symbol to locate the stock price for that company on a finance website.
Find the number labeled 'Last Trade.' This number indicates the last price at which shares of the stock were bought or sold, and it will give you a good idea of the price at which experts value the stock.
Locate the time labeled 'Trade Time.' This indicates the time the last trade occurred.
Locate the number labeled 'Change.' This number measures, in dollars, a stock price's change for that day.
Compare the number labeled 'Volume' to the number under 'Average Volume.' This shows how many stocks have changed hands that day compared to the average over an indicated period.
Look at the current price. This is the current established value of a share; the current price multiplied by the total number of shares is equal to the current judged value of an organization.