Updated for the 2026 rules

Free US tax and money calculatorsthat show their math.

Work out what you owe, what you keep, and what you can claim. Every figure is cited to the IRS, a state agency or the law itself.

47
free calculators
11
states for car tax
0
sign-ups or uploads

New for 2026

Built or updated for this year's rule changes

Browse every calculator

Pick a category, or search from the top of the page.

Tax and deductions

Paycheck and pay

Mortgage and property

Car tax, title and registration

Retirement and investing

Why KnownSum

Free, private, and every number is traceable. Maintained by KnownSum.

  • Every figure sourced

    Rates, caps and fees come from the IRS, state agencies and the law, never other calculator sites.

    See our sources

  • The math, shown

    Each result opens up step by step, so you can check the working yourself.

    How we calculate

  • Private by design

    Calculations run in your browser. Nothing you type is uploaded, and there is nothing to sign up for.

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