Time to FI Calculator

The Purpose (Why?)

To determine exactly what year or age you will cross your target FI threshold under various market conditions, rather than guessing a fixed duration. It allows you to model Coast FIRE and Barista FIRE adjustments to find the fastest path to work-life independence. (Note: Simulations use inflation-adjusted "Real Dollars")

How it Works

Input your current portfolio value, annual savings rate, savings growth rate, and expected annual retirement expenses. Choose a target SWR (Safe Withdrawal Rate) to calculate your FI target. The engine runs 500 Monte Carlo runs to determine the probability distribution of years to reach FI.

Foundational Research

Read the core research articles to understand safe withdrawal rates and why saving early is important:

ALGORITHMIC_NOTE: REAL_DOLLARS

Simulations use "Real Dollars" (inflation-adjusted). This means a 0% return maintains purchasing power, while positive returns approximate growth above inflation.

Input Specifications

PARAMETER	DETAILS
Current Portfolio Value ($)	Your starting invested portfolio balance. EXAMPLE: $100,000
Annual Savings ($)	The amount you save annually. EXAMPLE: $24,000
Savings Growth (%)	The annual rate at which your savings contributions increase. EXAMPLE: 3.0%
Annualized Expenses ($)	Your expected annual expenses in retirement (in today's dollars). EXAMPLE: $40,000
Target SWR (%)	The withdrawal rate you aim to use to calculate your FI target. EXAMPLE: 4.0%
Real Return (%)	Projected average annual investment return (inflation-adjusted). EXAMPLE: 7.0%
Standard Deviation (%)	Annual return standard deviation (volatility). EXAMPLE: 17.0%
Coast FIRE Mode	Models compounding existing portfolio value with zero ongoing savings additions. EXAMPLE: Checkbox
Barista FIRE Mode	Models transitioning to a part-time job that offsets part of your retirement expenses, reducing the required FI target. EXAMPLE: Checkbox
Part-Time Income ($/yr)	Income from part-time work during the transition phase (only used in Barista FIRE mode). EXAMPLE: $20,000

Benchmark Values

50/50 Portfolio (Stocks/Bonds)

R: 5.8% | σ: 6.1%
100% Stocks (S&P 500)

R: 7.0% | σ: 17.0%

Example Visualizations

Interactive Calculator

Ready to analyze your own portfolio numbers?

Launch Live Calculator

Example Output

View a high-fidelity, interactive sample report generated by this simulation engine.

View Sample Simulation Result

Frequently Asked Questions

Standard FIRE (the default mode) assumes you continuously contribute your annual savings until your portfolio is large enough to fund your full retirement expenses. Coast FIRE assumes you stop saving completely and let your current portfolio compound until it reaches your target FI amount. Barista FIRE assumes you work a part-time job to cover part of your living expenses, which reduces the total portfolio amount you need to accumulate.

Your target FI is calculated as Net Expenses / Target SWR. Under Barista FIRE, your net expenses are reduced by your part-time income: (Expenses - Part-Time Income) / Target SWR, which dramatically lowers the portfolio balance required to achieve independence.