This varies based on the loan type.
The amount of Federal Pell Grant funds you may receive over your lifetime is limited by federal law to be the equivalent of six years of Pell Grant funding. Since the amount of a scheduled Pell Grant award you can receive each award year is equal to 100%, the six-year equivalent is 600%.
Limits for Direct Subsidized Loans and Unsubsidized Loans can be found here.
You can find your federal student loan balances by logging into your account at StudentAid.gov as well as Pell Grant Lifetime Eligibility Used. If a student is concerned about exhausting their financial aid, they should contact their financial aid advisor to review remaining eligibility.