JM
JavaMoney — Finance Guru
MONTE CARLO TOOLKIT · MORTGAGE · DEBT PAYOFF · MARKET EXPLORER
by @cgfixit
Pure JS · Client-side · 2026
Assumptions
Advanced assumptions
Paths: simulated paths
Simulating…0%
How this works

Each path draws annual shocks from independent normal distributions. Buy side tracks net equity if liquidated; rent side invests the down payment + closing costs and the year-by-year cash-flow difference. We report P10/median/P90 bands, the share of paths where buying wins, and the median breakeven year. Returns are i.i.d. normal — fat tails and autocorrelation are not modeled.

📊
Run a simulation to see probabilistic outcomes
2,000 paths · 30-year horizon
VERDICT
BREAKEVEN
median year
BUY WINS
of paths at yr 30
Retirement Plan
Paths: real (inflation-adjusted)
Simulating…0%
How this works

Accumulation grows the portfolio with annual contributions under random real returns. At retirement we fix a real withdrawal (% of the retirement balance, or fixed dollars) and draw it each year while the remainder compounds stochastically. Because withdrawals are fixed in real dollars, a bad early run permanently impairs the path — that's sequence-of-returns risk. Success rate = share of paths that never hit zero.

🎯
Stress-test your retirement plan
success rate · ruin probability · terminal wealth
SUCCESS
RUIN PROB
MEDIAN END
P10 "BAD"
Mortgage Calculator
Monthly Payment
Total Interest: Total Paid: Payoff:
Amortization Schedule (first 24 months)
MoPaymentPrincipalInterestBalance
Your Debts
NameBalanceAPR %Min/mo
On top of all minimums, funneled into one debt.
How this works

Both strategies pay every debt its minimum, then funnel all remaining money into one priority debt. Avalanche attacks highest APR first to minimize interest. Snowball attacks smallest balance first for faster psychological wins. We compare both vs. minimums-only to show how much you save.

💳
Compare Avalanche vs Snowball
debt-free date · total interest · interest saved
DEBT-FREE
TOTAL INTEREST
SAVED VS MIN
WINNER
Payoff order —
    Zip Market Explorer
    Frozen reference dataset — price-to-rent & affordability scoring. Not live data.
    Affordability / value score
    Side-by-side comparison
    MarketPriceRent/moP/R RatioScore