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230 free calculators for mortgages, retirement, debt and taxes. Each one shows its formula and uses this year's IRS figures. No sign-up, and nothing you type leaves your browser.

How much house can I afford? When can I retire? Fastest way out of debt? What's my take-home pay?

Monthly mortgage payment

$2,275
principal & interest on $360,000 · 30 years
$450,000
20% · $90,000
6.50%
Add taxes, insurance & PMI →
2026 numbers

Most-used calculators

Start here, or search above for any of the 230.

Mortgage CalculatorEstimate your monthly principal, interest, taxes and insurance.Paycheck CalculatorEstimate net pay after taxes and deductions.Home Affordability CalculatorFind a comfortable price range based on your income and debts.FIRE CalculatorThe nest egg for financial independence at your spending.Auto Loan CalculatorMonthly payment for your next car, truck or SUV.Credit Card Payoff CalculatorHow long, and what it costs, to clear your balance.Rent vs Buy CalculatorCompare the long-run cost of renting versus owning.Compound Interest CalculatorSee what your savings can grow to with compound interest.

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Most calculators give you a number and ask you to trust it. Every SumWize calculator publishes the formula, the assumptions and a worked example you can check by hand.

  • Standard, published finance formulas
  • Tax figures straight from IRS, SSA and CMS, updated each January
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Read the methodology →
// monthly payment on an amortizing loan
M = P · r / (1 − (1 + r)−n)
P = 360,000 // $450,000 − 20% down
r = 0.065 / 12 = 0.0054167
n = 30 × 12 = 360 payments
M = $2,275.44
// check it on any calculator
The mathThe answer

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Guides that explain the math

Plain-English answers, each paired with the calculator that goes with it.

Home & mortgageHow much house can I afford?The 28/36 rule, and why the lender's number isn't yours.
RetirementThe 4% rule, explainedWhere it came from and when it breaks.
DebtHow to pay off debt fastSnowball, avalanche and what actually works.
Home & mortgageRent vs buyNet worth, not monthly cost, decides it.
AutoHow much car can I afford?The 20/4/10 rule with real numbers.
PaycheckYour paycheck and benefitsWhere every dollar of gross pay goes.
SavingsUnderstanding compound interestWhy starting early beats saving more.
RetirementThe complete retirement guideHow much you need and how to get there.

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