Your FICA Rate is fixed at 7.65%.  For every dollar you make you have to pay 7.65 cents.

For Example:

2021 Income is $10,000
You have to pay $765 in FICA Tax (Your Employer will also need to pay $765)

2021 Income is $20,000
You have to have to $1,530 in FICA Tax (Your Employer will also need to pay $1,530 in FICA Tax)

2021 Income is $45,000
You have to have to $3,442.50 in FICA Tax (Your Employer will also need to pay $3,442.50 in FICA Tax)

2021 Income is $80,000
You have to have to $6,120.00 in FICA Tax (Your Employer will also need to pay $6,120 in FICA Tax)