Who writes compoundcoast

Who runs this

I'm Chris Park — a machine-learning engineer, and the person behind every page here. I have been building signal-processing and AI systems since 2018, and among them time-series forecasting models on financial data. I am a long-term index investor working through the same accumulation, financial-independence, and drawdown questions the calculators answer, and these tools began as the ones I wanted for my own portfolio. They are public because publishing them cost nothing beyond what I had already built.

I am not a financial planner, an investment adviser, or an accountant, and nothing here is advice. None of that background makes a calculator correct either — that is what the printed formulas and the regression tests are for, and they are the part worth checking. The approach is practitioner-level: read the named sources directly — IRS revenue procedures, SSA actuarial tables, Damodaran's long-run return series, BLS inflation data — and turn them into tools that show their work rather than hiding it.

What this site covers

• Index investing and total-return backtesting across historical start dates.
• US investment taxation: qualified vs ordinary dividends, long-term gains, the net investment income tax.
• Financial-independence math — Coast, Barista, lean/fat — and the healthcare bridge before Medicare.
• Retirement drawdown: safe withdrawal rates, sequence-of-returns risk, and Roth conversion ladders.

Why the math is checkable instead

Since there is no financial credential to lean on, correctness has to be verifiable by the reader. Every calculator ships with a regression test that checks its output against hand-computed values or a published standard, and every formula is printed on the result page so a reader can follow the derivation. The retirement-drawdown tool, where the stakes are highest, gets the most scrutiny of all — its depletion math is replayed against every historical start year since 1928, in the real order returns arrived, and held to the same regression standard. The full standard is on the methodology page.

Corrections

Found an error or a stale figure? The correction policy and contact address are on the contact page. Corrections are made promptly and, when material, noted with a date.