## Step 1

Calculate your average portfolio size. For a given period, add the beginning and ending value of your portfolio, then divide the number by two. For example, suppose you want to calculate a monthly turnover in which the value is $22,000 on April 1 and $22,900 on April 30. The average portfolio size is $22,000 plus $22,900 divided by 2, or $22,450.

## Step 2

Figure your purchases for the period. Add together the amounts you spent during the period to buy securities. Say, for this example, that you spent $2,000.

## Step 3

Add up the total value of securities you sold during the period. For example, you might have sold $1,400 of securities in April.

## Step 4

Divide the lesser of purchases and sales by the average portfolio value. In this example, you bought more than you sold, so divide the sold amount, $1,400, by the average value, $22,450. The result, 6.24 percent, is your monthly portfolio turnover. You can figure weekly or annual portfolio turnover in a similar way.