Coast FIRE Calculator & Historical Retirement Plan Simulator

This simulator uses historical block bootstrapping to model realistic market behavior by sampling actual multi-year market periods. All values are shown in today's dollars, adjusted for inflation.

New to Coast FIRE? Once your investments are large enough that they can grow to fund retirement without any additional contributions, you've reached your Coast FIRE number. From that point on, you can reduce or stop saving and let compound growth do the rest. Use the Coast age field to choose when you'll stop contributing, or use the Coast FIRE tool below to find the earliest age your plan can coast.

Inputs

Timeline

30 year(s) actively saving, then 0 year(s) coasting, then 30 year(s) in retirement — 60 simulated years total.

Portfolio & Cash Flows

All amounts below are real (today's) dollars — held flat, never inflated forward.

Applied while actively saving — stops at your coast age.

Asset Allocation Strategy
Custom Glide Path

Add one control point per age where you want a specific asset mix — the simulation interpolates linearly between them and holds flat before the first and after the last. A single point (the default) is a fixed allocation for the whole simulation; add more to build a glide, e.g. stock-heavy in your 30s, shifting toward bonds by retirement. Points can fall before, at, or after your retirement age.

Total: 100%

Coast FIRE

Find the earliest age you could stop contributing and still reach retirement with at least the target success rate below, given everything else on this form.

Maximum Sustainable Spending

Find the highest annual spending level that still hits the target success rate below, given everything else on this form (starting portfolio, contributions, allocation, ages). This reflects your full plan — including accumulation-phase variance — so it isn't directly comparable to "4% rule"-style figures (see the Trinity-Study-comparable test below for that).

Trinity-Study-Comparable Rate

Freezes the median portfolio at retirement from your last run (ignoring accumulation entirely — no contributions, no pre-retirement years) and binary-searches the withdrawal percentage of that fixed balance until it hits the target success rate above. Because it starts from one fixed dollar amount and searches a rate directly, this number is directly comparable to the classic Trinity Study "safe withdrawal rate."

Simulation Settings

This run drew a random seed (61227748) — the next run will draw a different one, so results will vary slightly even with identical inputs.

Results

Success Rate
99.6%
Portfolio at Retirement
$6,590,232
Ending Portfolio
$38,245,046
6.5%/yr real · 4.5%/yr inflation
Retirement Drawdown
-39.2%
Typical largest decline after retirement
Retirement Low Point
$5,795,195
10th-percentile low point: $1,779,775
Typical lowest inflation-adjusted balance during retirement
Recovery Time
4.0 years
Unrecovered paths: 24%
Typical time required to regain the previous portfolio high
Initial Withdrawal Rate
0.6%
First-year retirement spending divided by retirement portfolio
Retirement Volatility
17%
Typical year-to-year swing in retirement returns (standard deviation)
Years Below Retirement Balance
1.0 years
Typical number of retirement years spent below the starting retirement balance
Failure Age
Age 91
Based on 8 of 2000 simulations that failed
Typical age when failed simulations ran out of money

Unless noted, values above are medians across all simulations — the typical outcome, not an average (skewed distributions make medians the more reliable summary here). Click the ending portfolio card to see that scenario's year-by-year log.

Median Portfolio Value by Year (real dollars)

2,000 simulations, 3–10 yr blocks, custom glide path, seed 61227748. Lock these settings