Appendix / Feature Explanations

Contribution cadence

You enter a monthly contribution. We keep the same total per ~30-day month:

• Monthly — full monthly once / month
• Bi-weekly — monthly ÷ (30/14), every 14 days
• Weekly — monthly ÷ (30/7), weekly
• Daily — monthly ÷ 30, daily

Deposit timing

Start of period (annuity-due) grows for the entire period; end of period (ordinary) grows starting next period.

“Also add each period’s interest”

On top of normal compounding, the interest amount is added again as an extra deposit that period (aggressive reinvestment).

Asset mix

Deterministic path uses the weighted mean return. Monte Carlo uses weighted mean + stdev (0 correlation by default).

Drawdown

• Fixed monthly withdrawal — subtract a fixed amount each period.
• 4% rule — withdraw 4% of beginning-of-year balance, spread evenly across the year.

Passive income target

Set a monthly passive-income goal (for example, $3000/mo) and the calculator estimates the first period where projected monthly interest reaches that level.

Output includes elapsed time, approximate months of contribution, and balance at the milestone. This planning tool lives in the right-most Planning panel and updates as you type.

Required contribution by deadline

Set a monthly passive-income goal plus a deadline in months. The calculator solves for the monthly contribution needed to reach that goal by the deadline under your current assumptions. This tool is also in the right-most Planning panel and updates while inputs change.

Goal seek

Solves for the required monthly contribution to reach your target final balance (bisection method).

Compare scenarios

Save a second configuration and overlay it on the chart to compare paths.

Monthly breakdown

When Show monthly breakdown is checked and compounding is Monthly (12), one continuous month-by-month table is shown in a scrollable panel.