Finance, but the math is honest.
Nine calculators and a handful of essays by a working engineer. Every assumption is on the page, every formula is linked, and nothing asks you to sign up first.
Assumptions in useSep 2026
Inflation (CPI, 12mo)3.4%
S&P 500, 10yr annualized10.1%
30yr fixed mortgage6.82%
Bond aggregate4.0%
Reference figures, not advice. Each calculator lets you override every one of them.
Calculators
Nine tools. Each one shows its work.01Compound InterestProject investment growth over time with annual contributions and compounding returns.→02Mortgage AmortizationBreak down monthly mortgage payments into principal and interest with a full amortization schedule.→03Retirement PlannerModel a life. Savings, employer match, drawdown, inflation — benchmarked against S&P 500, Nasdaq, and a bond floor.→04Loan CalculatorCalculate monthly payments and total interest for any auto, personal, or student loan.→05Budget PlannerThe 50/30/20 rule, with room to disagree. Needs, wants, savings — proportional, adjustable, honest.→06Emergency FundHow much runway you really need, and how many months until you get there at the pace you're saving now.→07Cost of DelayThe single most useful chart in personal finance: what every year of waiting to start actually costs you.→08Debt PayoffSnowball vs Avalanche across every debt you owe. Find the fastest, cheapest route to zero — and what they each feel like.→09Roth vs TraditionalFind out which IRA wins for your tax situation — now and at retirement. Apples-to-apples with break-even analysis.→
The whole picture, in two lists.
A calculator answers one question. Plan and Vault hold the answers you have to keep — what you still owe yourself, and what you already owe someone else.
Plantask checklist
Open a Roth IRAConfirm beneficiaries on all accountsCreate or update your will
Open Plan →Vaultaccounts & bills
Accounts, debts, insurance policiesBills and renewal datesKey dates and documents
Open Vault →Writing
All essays →Aug 29, 2026The Fluidity of the AI Growth PhaseWe are in the addiction phase of AI in the workplace. The efficiency gains are real, the dependency is real, and the economic ripple effects are only beginning. Here's how I'm thinking about what it means for portfolios — and for teaching the next generation.8 minMay 3, 2026Your Portfolio Should Age With YouThere's no single right allocation — but there is a direction of travel. Here's the decade-by-decade framework I wish I'd had from the start, and why the $100K milestone changes the math entirely.5 minApr 27, 2026Dear Younger Me: Just Open the Roth IRAI dropped $7,000–$14,000 into a Roth IRA early in my career, picked a boring S&P 500 ETF, and forgot about it. Fifteen years later it's worth over $40,000 — entirely tax-free. Here's what I'd tell my younger self.4 min