In futures and option contracts, it refers to the amount or units of an asset to be delivered as dictated by the contract. For instance, stock options involve a standard size of 100 shares. Therefore, a one option contract commands 100 shares. As far as commodities are concerned, a contract size is determined in terms of standard units or weight. As an example, a silver futures contract on the CME specifies 5,000 troy ounces.
For contracts on indices, the contract size is specified as a multiplier. For example, if the multiplier for a given exchange is 15 then the contract size is 15 times the value of its index. Therefore, if the index level is 1,700 then the contract value is
Contract value= multiplier × contract size = 1,700 × 15 = 25,500
