Personal Finance Calculators
Eight calculators for the money decisions people revisit most: how fast savings grow, what an extra mortgage payment saves, whether renting or buying comes out ahead, how big an emergency fund to keep, which debt to pay off first, and whether consolidating or refinancing actually pays off.
8 calculators · Last reviewed September 26, 2026
The calculators
Compound Interest
Project savings growth with monthly contributions
Mortgage Payoff
See the interest and years extra payments save
Income Tax Estimator
Estimate 2026 federal tax from the IRS brackets
Debt Consolidation
Compare total interest before and after consolidating
Refinance Break-Even
Find the month a refinance pays back its closing costs
Rent vs Buy
When owning beats renting, year by year
Debt Snowball vs Avalanche
Which payoff order saves more and finishes sooner
Emergency Fund
How many months of expenses to keep in cash
Which calculator answers your question?
How much will my savings grow if I add to them every month?
Compound InterestHow much interest and time do extra mortgage payments save?
Mortgage PayoffRoughly what will I owe in federal income tax for 2026?
Income Tax EstimatorDoes rolling my debts into one loan reduce total interest?
Debt ConsolidationHow many months until a refinance earns back its closing costs?
Refinance Break-EvenAfter how many years does buying a home beat renting and investing the difference?
Rent vs BuyShould I pay off the highest-rate debt or the smallest balance first?
Debt Snowball vs AvalancheHow much cash should I keep for emergencies, and how long will it take to save?
Emergency FundKey ideas behind these calculators
Compounding
Interest earns interest. Growth depends on the rate per period and the number of periods far more than on the starting balance, which is why time in the market matters so much and why high-rate debt grows so fast.
Amortization
Each fixed loan payment covers that month’s interest first; only the remainder reduces principal. Early payments are mostly interest, so extra principal paid early in a loan saves far more than the same amount paid late.
Break-even
When you pay a cost now to save money later, divide the upfront cost by the monthly saving. That is the number of months before the move pays off. If you might sell, move or pay off the loan sooner, it may never break even.
Marginal vs. effective tax rate
Your marginal rate is the rate on your last dollar of taxable income. Your effective rate is total tax divided by income, and it is always lower, because each bracket only taxes the slice of income that falls inside it.
What these estimates leave out
- State and local income taxes, credits and most deductions beyond the standard deduction.
- Taxes on investment gains, and inflation, unless a calculator says it includes them.
- Prepayment penalties, loan fees you do not enter, and the effect of a new loan on your credit score.
- Your full financial picture. For a large decision, check the numbers against your loan documents or with a licensed professional.
See the full disclaimer and how we build and check the calculators.
Financial guides
All guidesDebt Avalanche vs. Snowball: Which Payoff Method Is Better?
Avalanche pays the least interest; snowball clears accounts sooner. A worked example shows a $383 gap, and what research says about sticking with it.
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Extra $100 a Month on Your Mortgage: How Much It Saves
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Mortgage Recast: How It Works and How It Compares to a Refi
A recast lowers your payment after a lump-sum principal payment and keeps your rate. See the math on a $40,000 recast and how it compares to a refinance.
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How to Protect Your Savings From Inflation in 2026
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Mortgage Interest vs. Inflation: Your Real Borrowing Cost
At a 7.03% mortgage rate and 3.4% inflation, the real cost of borrowing is about 3.5%. How to calculate it, and whether to prepay or invest.
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How Much Emergency Fund Do You Need? 3 to 12 Months
Start from 3 to 6 months of essential expenses and adjust for your income and household. A worked $15,000 example, and where to keep the money.
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