Free money calculators that show their math
Mortgage, auto, paycheck, tax, savings and everyday calculators built for U.S. households — fast, private (everything runs in your browser) and updated for 2026.
Mortgage & Home
Auto
Loans & Debt
Savings & Retirement
- Compound Interest CalculatorWatch savings grow with compounding and monthly deposits.
- Savings Goal CalculatorThe monthly amount needed to hit a goal by your deadline.
- Retirement / 401(k) Calculator401(k) projection with employer match and the 4% rule.
- Inflation CalculatorFuture prices and the shrinking buying power of a dollar.
Taxes & Income
Everyday, Health & Dates
- Tip CalculatorTip, total and split the bill between friends.
- Percentage CalculatorPercent of a number, what percent, and percent change.
- BMI CalculatorBody mass index, category and healthy weight range.
- Age CalculatorExact age in years, months and days, plus next birthday.
- Date Difference CalculatorDays, weeks and weekdays between any two dates.
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Why PayPlanCalc?
Every calculator uses the standard formulas lenders, the IRS and financial planners use, and each page explains the formula with a worked example so you can check the numbers yourself. Tax and paycheck tools use official 2026 IRS and Social Security figures. Nothing you type is sent to a server — all calculations happen on your device.