§ The full catalog
Every calculator, one quiet domain.
Organized the way you’d find them on a library shelf — by the part of your financial life they touch. Free, no sign-up, math you can audit.
DCA Calculator
Backtest dollar-cost averaging against real historical prices — Bitcoin included.
Open →Compound Interest
Watch contributions compound across decades — future value, total interest, and the growth multiple.
Open →Investment Growth
Lump sum plus growing contributions — what your portfolio is really worth after inflation.
Open →Stock Return
Profit, total return, and annualized (CAGR) return on a stock trade — fees and dividends included.
Open →Position Size
How many shares to buy so a stopped-out trade loses only what you risk — the 2% rule, with reward-to-risk.
Open →Inflation
What a dollar from one year is worth in another — cumulative and annual inflation from official CPI-U data.
Open →Bond Yield
Current yield and yield to maturity (YTM) for any coupon bond — from face value, coupon, maturity, and price.
Open →Cost of Waiting
What delaying investing really costs — start now vs wait a few years, where the lost compounding dwarfs the skipped contributions.
Open →Dividend
Dividend income, the rising yield on cost as the payout grows, and the snowball of reinvesting (DRIP).
Open →Lump Sum vs DCA
Settle the debate with real data — invest all at once or spread it out?
Open →Mortgage Calculator
Full PITI with PMI, taxes, insurance, and a complete amortization schedule.
Open →Affordability
How much house can you afford? Income, debts, and the 28/36 rule.
Open →Refinance Break-Even
How many months until a refinance pays back its closing costs.
Open →Rent vs Buy
The real long-run cost of renting versus owning, opportunity cost included.
Open →Mortgage Recast
Lower your payment with a lump sum to principal — re-amortized, no refinance.
Open →Biweekly Mortgage
Pay half every two weeks and knock years off your mortgage.
Open →Payoff vs Invest
Pay extra on the mortgage or invest the difference? A fair, same-budget comparison of which builds more wealth.
Open →HELOC
Home equity line of credit — the interest-only draw payment, the amortized repayment payment, and the shock between them.
Open →Retirement / FIRE
Your FIRE number, savings rate, and the year you could retire.
Open →401(k) Calculator
Employer match, contribution limits, and decades of projected growth.
Open →Roth vs Traditional
Tax now or tax later — compare Roth and traditional retirement accounts.
Open →Coast FIRE
The amount invested today that coasts to your FIRE number — no more saving.
Open →Retirement Withdrawal
How long will your savings last? Draw down a nest egg with the 4% rule and an inflation-adjusted withdrawal.
Open →Lean vs Fat FIRE
Lean, Regular, and Fat FIRE side by side — three lifestyle tiers, three FIRE numbers, and the years between them.
Open →HSA Calculator
Grow a Health Savings Account to retirement — the triple tax advantage, in dollars, versus a taxable account.
Open →RMD Calculator
Required minimum distributions by age from the IRS Uniform Lifetime Table — this year’s RMD and the full schedule.
Open →Credit Card Payoff
How fast a balance disappears — and what avalanche vs snowball saves.
Open →Auto Loan
Price, trade-in, tax, term, and APR with a full payment schedule.
Open →Loan Payoff
See how fast extra payments kill any loan.
Open →Personal Loan
Loan amount, APR, term, and origination fee — with effective APR and a full payment schedule.
Open →Debt-to-Income
Your front-end and back-end DTI — the ratio every lender checks, against the 28/36 rule and the 43% cap.
Open →Emergency Fund
How big your safety net should be, and how fast you can build it.
Open →Savings Goal
Work backward from a goal to the monthly amount you need to save.
Open →Net Worth
Add up everything you own minus everything you owe — net worth, debt-to-asset ratio, and where it sits.
Open →CD Calculator
Lock a lump sum at a fixed APY — guaranteed maturity value, interest earned, and the cost of breaking it early.
Open →APR vs APY
Convert a nominal rate (APR) to its effective yield (APY) at any compounding frequency — and compare offers fairly.
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