You don’t claim “dependents” on the FAFSA. The FAFSA will ask you to verify household size and the rules for who is in your household are far different than the tax rules used by the IRS to determine a dependent for tax purposes.
If you are a dependent student as determined by the FAFSA—which means you will need to provide information from your FAFSA parent(s)—the FAFSA will ask for the household size of the parent to be reported. If you are an independent student as determined by the FAFSA—which means you will not provide parent information—the FAFSA will ask for your household size.