Financial Runway Planner

Plan

Plan name

Your plans

Current year Year of death Retirement year Current net worth Beta mode SPX beta Simulations Tax on withdrawals %

Income

Lifestyle

Use builder

Describe how you want to live; the builder prices it year by year.

Household

Area Adults Your birth year

Kids

Housing

Housing Monthly rent Home price Purchase year Tax, insurance, upkeep %/yr Down payment % Mortgage rate % Term yrs Monthly mortgage Paid off in Appreciation (real) %/yr

Counts toward net worth (leave it out of Current net worth); sold for renting if the portfolio would run out.

Household help

While kids are at home Help

Travel

Domestic trips / yr Nights each International / yr Nights each Flights Hotels Domestic with kids International with kids Kids fly

Private is priced per trip for the whole plane (charter, ~$80K domestic, ~$300K international round trip), so it doesn't grow with the family.

Kids (until 18) join that many of the year's trips, never more than you take.

Everyday living

Style

Health

Employer coverage Covered through

Private insurance after that, then Medicare at 65 if your birth year is set.

Expenditures

Run-out risk -- Probability of depleting before death

Expected terminal wealth -- Mean final wealth, current dollars

Current SPX beta -- Allocation for the first plan year

Needed for 1% risk -- Starting net worth for the target run-out risk

Y-axis cap 90%

Depleted only

Category	This year	Peak year	Peak	Lifetime total
No spending yet.

Plan year	Sampled year	Start wealth	Income	Expenses	Withdrawal tax	SPX return	Risk-free	SPX excess	SPX beta	Inflation	SPX real	Portfolio nominal	Portfolio real	End wealth	Home equity	Status
No results yet.

No dynamic policy yet

Set beta mode to Dynamic and run a simulation to inspect the year-by-wealth beta policy.

Optimal SPX beta vs wealth

Y-axis

Beta alternatives

Wealth bucket

SPX beta	Run-out risk	Expected terminal wealth	Choice
Run dynamic beta to inspect beta alternatives.

Policy path explorer

Run dynamic beta to inspect a policy path.

Override beta Override years Return assumption Historical year

Plan year	Start wealth	Forced beta	Sampled year	SPX return	Inflation	End wealth	Policy beta next	Risk from node
Run dynamic beta to inspect a policy path.

Historical data

Simulations sample one historical year at a time, with replacement, from the loaded history. Each sampled year supplies an S&P 500 total return, a 3-month T-bill return, and CPI inflation.

Return model

Portfolio nominal return is the T-bill return plus SPX beta times the S&P 500 excess return over T-bills. It is converted to current dollars by dividing by that year's inflation factor.

Dynamic beta

Backward dynamic programming over plan year and wealth, using a zero bucket plus 180 log-spaced buckets from $10K to $1T and betas from 0.0 to 1.5 in 0.1 steps. The solver builds several candidate policies, from minimum run-out risk to maximum expected wealth, with risk-penalty policies in between. The beta for a year is chosen before that year's return is drawn.

Frontier

Each dynamic run also solves the policy with scenario-calibrated risk penalties. Every resulting policy is simulated from your net worth on the same 10,000 extra paths, and the chart plots its expected and median terminal wealth against its run-out risk. Expected wealth is pulled up by a few very good paths; the median is the typical outcome. The run uses the policy with the most median wealth among those whose run-out risk is at most 0.5% or the lowest any policy reaches: below 0.5%, less risk isn't worth giving up wealth for.

How much you need

After each run, 20,000 extra paths of historical years are drawn. For each one, a bisection finds the least starting net worth that survives it under the same policy and cash flows. The share of paths whose threshold is above an amount is the run-out risk at that amount, so the needed net worth for a target risk is a percentile of the thresholds.

Home

An owned home is an asset: its value grows at the plan's real appreciation rate and its equity (value less mortgage) counts toward net worth and terminal wealth. If a path's portfolio would run out, the home is sold that year for its value less 6% selling costs and the mortgage, its costs stop, and rent at 4% of its value starts. Run-out risk means running out even after selling. The beta policy knows about the sale: it is solved first for life after a sale and then for owning, so it can take more stock risk while the home backs the portfolio. Mortgage payments and balances shrink with an assumed 2.5% inflation.

Taxes

Income is entered after tax. Spending that income doesn't cover is withdrawn from the portfolio, and selling costs tax on the gains: covering a shortfall S at the plan's withdrawal tax rate t takes S / (1 − t). The default 15% approximates California taxes on a taxable account where about 60% of each sale is gain. Dividends taxed while invested, account types, and borrowing against the portfolio are not modeled.

Lifestyle builder

The builder prices a described lifestyle as dated annual expenses in today's dollars. Kid costs follow each kid's age: childcare to 4, school 5–17, college 18–21. Local costs (childcare, school, help, everyday living) are priced for SF/NYC and scaled down for cheaper areas. Every line can be overridden or moved to a manual row. Above-inflation cost growth is not modeled; taxes are handled by the plan's withdrawal tax.

Cash flows

Income and expenditures are annual current-dollar flows. Start and end years can be fixed or tied to the plan's current year and year of death. Lifestyle lines use fixed years; one-time costs such as a home purchase are a single-year flow.

Timing

Within each year, returns compound continuously and net cash flow arrives continuously. A path is depleted when current-dollar wealth reaches zero.

Limits

This is a historical bootstrap, not a forecast. It ignores taxes, account types, fees, allocation beyond SPX beta, spending adjustments, serial correlation between years, and valuation-based expected returns.