All calculators
Every tool on frugalmath, organized by category. Type to filter.
Savings
Savings goal calculator
Time to reach a savings target, or the monthly amount needed.
Emergency fund calculator
Size your fund, then see how inflation and interest move the target.
High-Yield Savings Calculator
Project the interest, then model a rate cut and the tax on it.
CD vs. Savings Calculator
The held-to-term winner, plus the penalty break-even for breaking a CD early.
Sinking Fund Calculator
Split one account across several goals, and get the monthly for each.
Savings Rate Calculator
The share of income you save, and the years to financial independence it buys.
Monthly Savings Calculator
The monthly deposit to hit a goal by a date, and why the rate barely moves it.
Time to First $100k Calculator
How long the first $100,000 takes, and why every $100k after it comes faster.
Debt
Credit card minimum payment
How long minimum payments really take, and why the formula decides it.
Debt Avalanche Calculator
Avalanche vs snowball on the same debts, and when the choice barely matters.
Debt Snowball Calculator
What smallest-first costs in interest, and when your first debt disappears.
Loan Amortization Calculator
The payment where principal finally beats interest, and how front-loaded the interest is.
Student Loan Calculator
Standard vs income-driven repayment, with the forgiveness and tax math.
Auto Loan Calculator
Payment and total interest, plus what a dealer rate markup really costs.
Credit Card Payoff Calculator
Pick a payoff date and get the payment, or enter a payment and get the date.
Debt-to-Income Calculator
Front-end and back-end DTI, and the gap between what lenders approve and what's affordable.
Personal Loan Calculator
Payment and total interest, plus the APR you really pay once the origination fee is in.
Investing
Compound interest calculator
Future value with compounding, then the real number after inflation and tax.
Dollar-Cost Averaging Calculator
DCA a lump sum or invest it all today, run on identical numbers.
Investment Fee Calculator
What an expense ratio really costs over decades, plus the advisor and plan fees stacked on top.
Index Fund Calculator
Long-horizon growth net of fees, plus the sequence-of-returns risk the smooth line hides.
Rule of 72 Calculator
Years to double your money, the estimate against the exact math, and where the shortcut drifts.
Future Value Calculator
What a lump sum grows to, what it's worth after inflation, and how far the rate assumption moves it.
Annualized Return Calculator
The yearly rate behind a total gain, plus the money-weighted return CAGR gets wrong.
Inflation-Adjusted Return Calculator
Turn a nominal return into a real one, and see what a lump sum buys in today's dollars.
Retirement
401(k) Calculator
Project your balance, and see the employer match as the instant return it is.
FIRE number calculator
Your number at 3%, 3.5%, and 4% withdrawal rates, plus the horizon trap.
Roth IRA Calculator
Tax-free growth, plus the honest Roth-vs-Traditional call decided by your tax rate now versus later.
Roth vs Traditional IRA Calculator
The break-even tax rate that decides it, and why return and horizon don't.
Safe Withdrawal Rate Calculator
The safe rate is set by your stock/bond mix, not a universal 4%.
Social Security Claiming Calculator
Break-even age for claiming at 62, 67, or 70, and how investing early checks moves it.
Taxes
Federal Tax Bracket Calculator
Your bracket, and the effective rate you actually pay after the math.
Marginal vs. Effective Tax Rate Calculator
Both rates from the bracket math, plus your real next-dollar rate once FICA and state stack on.
Standard vs. Itemized Deduction Calculator
Which deduction wins, the threshold you must clear, and what itemizing saves.
Capital Gains Tax Calculator
Short-term vs long-term, with the gain stacked on your income the way the IRS does it.
Real estate
Mortgage payment calculator
Monthly payment with PMI, and the month PMI actually drops off.
Refinance Calculator
Closing-cost break-even, plus the lifetime interest a lower payment can hide.
Rent vs Buy Calculator
Rent or buy as a net-worth race with the down payment invested, plus the 5% rule check.
Mortgage Payoff Calculator
Interest and years saved by extra payments, and whether prepaying beats investing.
House Affordability Calculator
How much house the 28/36 rule allows, and the gap to what a lender will approve.