FIcology 101

Getting started

• Fill in the Inputs tab on the left — the chart, table, and summary cards update instantly. Use the Assumptions tab for return rates and the Settings tab for projection length and table options.
• The table auto-switches to retirement withdrawals at your Target Retire Age. Your FI Number is shown as a milestone — it auto-calculates from Annual Expenses ÷ Safe Withdrawal Rate, or type a value to override it and click ↺ Reset to auto-calculate to go back.
• In the table, the Contribution / Withdrawal and Return % columns are editable (pencil icon in header). Click any cell to override it for a specific year. An amber highlight and ↺ icon appear when a cell has a manual override — click ↺ to restore just that cell to its calculated default.
• Phase Fill Down (Settings tab) cascades a cell edit to all rows below it within the same phase. Stops at Accumulation → Coasting → Retirement boundaries so edits don't accidentally overwrite other phases.
• Auto-Coast (Settings tab) automatically switches to $0 contributions once you hit Coast FI, letting compound growth carry you the rest of the way to retirement.
• Clear Manual Table Edits (link below the input panel) removes all cell overrides at once and restores the calculated defaults.
• Phase colors: blue = accumulation, yellow = coasting (no contributions, not yet withdrawing), green = retirement.

Scenarios & tips

• Simulate a market crash: click a Return % cell and enter a negative number (e.g., -20%). Repeat for each crash year. Click ↺ on each cell when done to restore it.
• Sabbatical or career break: override the Contribution cell to $0 for the years you won't be saving.
• Big one-time expense: enter a large negative number in a Contribution cell (e.g., -$50,000 for a home down payment) — it pulls that amount from the portfolio that year.
• Part-time income in retirement: override a retirement year's withdrawal cell to a smaller negative number, or even a positive number if your part-time income covers expenses.
• Lean FIRE vs. Fat FIRE: type a custom value in the FI Number field to compare different savings targets.
• Variable spending in retirement: override individual retirement withdrawal cells to model spending less during a market downturn.
• See the coast FI effect: check Auto-Coast and watch your FI Date — sometimes stopping contributions early moves your FI date by only a year or two; sometimes much more.