Spreadsheets & Calculators
Tools that show their work.
Free spreadsheets built on the same arithmetic as the essays. No signup, no email, no macros.
Most personal finance calculators hand you a number and hide the formula. That is backwards. A projection is only as good as the assumptions underneath it, and if you cannot see them, you cannot argue with them. Every sheet here puts its assumptions in labeled cells you can edit, and every result is a live formula rather than a figure typed in by hand.
They are plain .xlsx files. They open in Excel, Numbers, LibreOffice, and Google Sheets. Nothing runs, nothing phones home, and nothing asks for your email address.
Available now
4 toolsNewest first. More on the way, roughly one a month.
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Investment Fee Drag Calculator
What are your fees actually costing you, in dollars and in years of extra saving? List your holdings, add the advisory layer, and a month-by-month engine prices the whole arrangement. The ladder shows what switching would be worth before you switch.
Details and download → -
DCF Valuation Model
A ten-year discounted cash flow model for valuing a single company, with an explicit WACC build and a sensitivity grid across discount rate and terminal growth. It also runs backwards: the reverse DCF solves for the growth rate today's share price already assumes, which is usually the more useful number.
Details and download → -
Order of Operations Allocator
Where does the next dollar go? Enter your income, expenses, debts, and account room, and a nine-step waterfall draws what each step needs before passing the rest down. The contribution limits are left blank on purpose, because a limit typed into a spreadsheet goes stale without telling you.
Details and download → -
Savings Rate & FIRE Tracker
Twelve rows a year is the whole habit. Log income, spending, and dollars invested, and the dashboard returns your savings rate, your progress to the target, your coast number, and how far off financial independence is at your current pace. Includes the savings rate table that shows why a 50% rate takes about 17 years and a 10% rate takes about 51.
Details and download →