Money math, done privately.
Free finance calculators for mortgages, loans, savings and paychecks. Your income and loan numbers are sensitive — so every calculation happens on your device. Nothing is uploaded, stored, or sold.
Mortgage Calculator
Full monthly payment breakdown — principal & interest, property tax, home insurance and PMI — plus total interest over the life of the loan.
Loan Calculator
Monthly payment and total cost for any loan — auto, personal or student. See how extra payments shorten your payoff and cut interest.
Compound Interest Calculator
Project how savings grow with regular contributions and compounding — with a year-by-year chart showing the snowball in action.
Paycheck Calculator
Estimate your take-home pay after 2026 federal tax, FICA and state tax — with 401(k) and health insurance deductions handled correctly.
401(k) Calculator
Project your retirement balance with contributions, employer match and salary growth — in nominal and today's dollars.
Methodology & Privacy
Every formula, every tax figure and its official source (IRS / SSA), and exactly what this site does with your data: nothing.
Why MMult?
Private by design. Competing calculator sites quietly log your salary, loan amount and home price — some even sell "calculator leads" to mortgage brokers. MMult has no backend: your numbers are processed by JavaScript in your browser and go nowhere.
Transparent methodology. Every calculator publishes its formulas and the official data sources behind them (IRS Rev. Proc. 2025-32, SSA 2026 wage base). You can verify the math yourself.
Updated for 2026. Tax brackets, standard deductions, FICA limits and 401(k) contribution limits reflect tax year 2026 rules.
Frequently asked questions
Are these calculators really free?
Yes — no sign-up, no trial, no paywall. The site is supported by unobtrusive display advertising, never by selling user data.
Is my financial data private?
Yes. All calculations run 100% client-side in your browser. The numbers you type are never transmitted to any server. See our privacy & methodology page.
How accurate are the results?
Formulas follow standard amortization and IRS/SSA published figures for tax year 2026. Paycheck results are estimates — actual withholding varies with your W-4, local taxes and employer benefits. See the methodology note on each tool.
What is the monthly mortgage payment formula?
M = P × [ r(1+r)n ] / [ (1+r)n − 1 ], where P is the loan amount, r the monthly interest rate and n the number of payments. Our mortgage calculator adds taxes, insurance and PMI on top.
Can I use these calculators outside the US?
The mortgage, loan, compound interest and 401(k) tools work with any currency and interest convention. The paycheck calculator is US-specific (federal + FICA + state tax) and the 401(k) tool follows US retirement account rules.