Simply put, Disposable Income (or DI), is the amount of net income remaining after all regular monthly expenses are deducted. The size of this amount can determine whether you file a chapter 7 or 13 bankruptcy.
Just take your total monthly net income and deducts all monthly expenses that are reasonable and necessary for your support or that of a dependent. The amount of money left over, if any, is the DI. Find out more here!