This online calculator contains a description of Exchange margin requirements for various positions in put options, call options, combination put-call positions and underlying positions offset by option positions. The equity and index option strategies available for selection in this calculator are among those most widely used by investors. Margin amounts computed by this calculator reflect exchange-minimum requirements of the Chicago Board Options Exchange. Margin amounts required by specific brokerage firms may be higher. Further, this calculator's computations reflect only the Exchange's initial margin requirements; ongoing maintenance margin requirements may be necessary, and are indicated where appropriate but not calculated.