The FI Calculator

Plan your journey to Financial Independence and stress-test your portfolio against market volatility.

Financial Independence, Retire Early (FIRE) is a movement dedicated to achieving financial freedom long before traditional retirement age. This calculator helps you map out your journey.

1. Your Financial Snapshot & Goals

Start by entering your current financial details and your desired retirement lifestyle. This information is used to calculate your basic FIRE (Financial Independence, Retire Early) number and a baseline projection for when you might reach it.

Major Life Events, Lump Sums & Recurring Incomes

Add one-time, temporary, or recurring cash flows (expenses or income) that will impact your plan. Examples: college costs, inheritance, home sale, sabbatical, pensions, rental income, Social Security, or part-time work. For recurring income, use 'Income' with a start and end age.

Current Situation

Retirement Goals

Assumptions & Scenarios

2. Your FIRE Projection Summary

This is your baseline projection. It assumes your investment returns are the same every year. Use this as a starting point before stress-testing your plan in the Advanced Simulation section below.

Adjusted FIRE Number

Savings for expenses not covered by post-FIRE income.

Time to FIRE

Time to reach Adjusted FIRE Number.

Age at FIRE

Your age when Adjusted FIRE Number is met.

FI Date

Calendar date of reaching Adjusted FIRE Number.

Savings Rate

Percentage of gross income saved annually.

Years of Expenses Covered (Current)

Current savings cover this many years of retirement expenses.

Total Contributions to FIRE

Total amount contributed until FIRE.

Total Growth to FIRE

Total investment gains by FIRE.

Savings at FIRE

Projected savings when FIRE is reached.

Coast FIRE Number

Amount needed at Coast Age to reach FIRE by Target Age with no further savings.

Annual Savings Growth (Pre-FIRE, Real Returns)

YearAgeStarting SavingsContributionsInvestment Growth (Real)EventsEnding Savings

Detailed Monthly Growth (First Months Pre-FIRE)

MonthDateAgeStarting SavingsContributionGrowth (Real)EventsEnding Savings

Post-FIRE Annual Projection (Baseline Scenario - Real Values)

Based on Post-FIRE returns. Continues up to age 95 or until savings depleted.

Year (Post-FIRE)AgeStarting SavingsGrowth (Real)Net Withdrawal from SavingsTotal Income Rec'dEnding Savings

What-If Levers: Instantly See the Impact

Current: 15,000
Current: 40,000
Current: 0
Projected FIRE Age
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3. "One More Year" Scenario Analysis

This section helps you quantify the financial benefit of working a few extra years past your projected FIRE date. See how it impacts your final portfolio value and the lifestyle it can support.

Impact of Working 1 Extra Year(s)

New Portfolio Value at Retirement

Projected total savings after extra working years.

New Retirement Age

Your age after working extra years.

Increased Yearly Spending Possible

If maintaining original withdrawal rate and retirement duration to age 95.

Or, Funds Last Until Age

If maintaining original spending level (projects up to age 95).

4. Potential Early Retirement Income & Capital Growth

This chart shows how different savings rates impact your accumulated capital (dashed lines, right axis) and the sustainable monthly income it could generate (solid lines, left axis).

5. Advanced Retirement Simulation

This is the most important step for stress-testing your plan. While the baseline projection assumes constant returns every year, this section simulates real-world uncertainty.

Historical Cycles (The "Reality Check"): This method tests your plan against the actual, recorded market history. It answers the question: "How would my plan have survived the best and worst periods of the last century?" Its strength is using real-world data, including every major crash and boom exactly as they happened.

Monte Carlo (The "What-If Engine"): This method is a powerful futuristic tool. Instead of replaying the past, it generates thousands of unique, random futures based on *your* assumptions for average returns and market volatility. It answers the question: "If the future is as good or bad as I expect, what are my chances of success?" Its strength is its flexibility to model scenarios that haven't occurred in the past. The results are a direct reflection of the parameters you set.

Stocks Bonds
60% / 40%

Based on S&P 500 & 10-Yr Treasury data from 1928-2023.

This rule reduces your spending temporarily when your portfolio is down, helping it recover faster. Spending reverts to normal once the portfolio returns to its initial value.

Success Rate

Chance of portfolio lasting to age 95.

Median Final Value

50th percentile portfolio value at age 95.

10th Percentile Value

A "bad outcome" scenario at age 95.

90th Percentile Value

A "good outcome" scenario at age 95.

Years w/ Reduced Spending

Median number of years spending was cut.

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FIRE Calculator Summary

© The FI Calculator. This work is licensed under a CC BY-NC-SA 4.0 License View on GitHub

Disclaimer: This tool is for informational and illustrative purposes only and does not constitute financial, investment, or tax advice. The projections are based on the assumptions you provide and do not guarantee future results. All financial decisions should be made with the guidance of a qualified professional.

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