The easiest way to estimate your monthly repayments is to use our loan simulator tool below.
Generally, your monthly payments under Income-Based Repayment (IBR), Pay As You Earn (PAYE), and Revised Pay As You Earn (REPAYE) are calculated as 10% or 15% of your "discretionary income", which is your income minus 150% of the poverty level for your family size and state. If you earn below 150% of the poverty level, your required loan payment will be $0. If you earn more, your loan payment will be 10% or 15% of whatever you earn above that amount.
I know its a bit complex but its worth getting your head around. I recommend again you use the loan simulator to help.