A constant that each option has that is used to calculate its dollar value. Equity options have a multiplier of 100. This means that an option contract can be converted into a stock position of 100 shares. One multiplies the price of the option by its multiplier to determine the total cost of that particular option. Stock IKL has a 35-strike call that is trading for $2½. To determine the cost of buying that option one time, you multiply the cost of the option ($2 ½) by its multiplier (100) to get the total capital needed ($250).