Porch Math: A Retirement Operating System for Living Under Uncertainty

Retirement is not a magic-number problem. It is an operating problem. The 4% rule, Monte Carlo success rates, asset allocation, bond tents, Social Security, taxes, annuities, healthcare, and long-term care all answer real questions. None of them, alone, tells a household what to do when markets fall, rules change, health changes, or the person who built the spreadsheet can no longer run it. Porch Math goes inside the research behind long-term investing and retirement withdrawals, then brings it down to porch level: two friends arguing in plain English, five fictional households facing different constraints, and careful study autopsies showing what the evidence actually establishes-and where it stops. No magic number. No fake certainty. Just research, tradeoffs, and a system designed to remain usable while the future changes.