How we calculate

Last updated: October 30, 2026

Every calculator runs in your browser using standard formulas, so your numbers never leave your device.

Loans and debt

Loan payments use the standard amortization formula, with interest accruing monthly on the remaining balance. Debt payoff plans apply each month's interest, pay every minimum, and send all extra money to one priority debt, rolling freed-up payments forward.

Investing

Growth calculators compound a constant annual return monthly, add your contributions each month, and show inflation-adjusted values by dividing by cumulative inflation.

Taxes

Federal calculations use the 2026 inflation-adjusted brackets, standard deductions and Social Security wage base published by the IRS and the Social Security Administration. State rates, brackets and deductions are based on the Tax Foundation's published 2026 state tables. We simplify some state rules, so results are estimates.

Updates

We review tax figures each year when new numbers are released, usually in the fall for federal figures and early in the year for state tables.

Corrections

If you find an error, please tell us at oneclicktool.tech@gmail.com and we will review it.