Federal tax income is based on numerous factors. Generally, as taxable income increases, so do the tax rates because tax brackets increase the more taxable income you have.
Currently, the tax brackets range from 10% to 37%. Keep in mind that income up to the amount of the standard deduction or the total of your itemized deductions is not taxed.
Your calculation of federal tax will also depend on your filing status, deductions, credits taken and your deductions. A lot of factors come into play when calculating your federal income tax. Without seeing the components of your return, it is hard to tell you what exactly applies to you.
A great tool to use to see how your tax is calculated is the Income Tax Calculator 2020.