Available to Promis (ATP) relates to the uncommitted portion of a company’s inventory and planned production maintained in the master schedule to support customer-order promising. The ATP quantity is the uncommitted inventory balance in the first period and is normally calculated for each period in which an MPS receipt is scheduled. In the first period, ATP includes on-hand inventory less customer orders that are due and overdue. Three methods of calculation are used: discrete ATP, cumulative ATP with look ahead, and cumulative ATP without look ahead. Disclaimer Our content is not in any way legal advice or binding. The information provided by might not be the official legal or full definition. Also when pursuing a specific transaction you are encouraged to conduct your own due diligence and to consult legal counsel as appropriate.