Personal Finance What-If Simulator (No Account)

Enter age, income, expenses, rent, loan, portfolio and retirement contributions, pick a what-if (promotion, unemployment gap, new child, early retirement) and get the whole picture: a 30-year net worth projection run through a seeded Monte Carlo simulation (default 1,000 trials, log-normal real returns blended from your stock/bond allocation — stocks 7% mean/17% volatility, bonds 2.5%/6% historical real anchors), reported as median with 10th–90th percentile bands. The tax engine uses the actual 2026 US numbers: seven federal brackets for single and married-filing-jointly, $16,100/$32,200 standard deductions, 6.2% Social Security up to the $184,500 wage base, 1.45% Medicare plus the 0.9% surtax, and a flat state-tax placeholder you can dial in. A 401(k) card shows whether your deferral captures the full employer match and what leaving money on the table costs per year. The Roth conversion ladder card sizes conversions that fill your 12% bracket in early-retirement gap years, honouring the 5-year seasoning rule and RMD age 73. A buy-vs-rent break-even and a refinance break-even (closing costs ÷ monthly saving) round it out. Everything is computed from a fixed seed so the same inputs replay the same projection; results are planning estimates, not tax advice.