Calculate your target portfolio size for early retirement with a comfortable lifestyle.
Commonly between 3% and 5%.
Long-term average growth. Adjust based on your risk tolerance.
Amount you save and invest each year. Set to 0 if retired.
Your Fat FIRE Numbers
Understanding the Fat FIRE Calculator
The "Fat FIRE" movement represents a phase of Financial Independence, Retire Early (FIRE) where individuals aim to retire with a significantly larger nest egg than traditional FIRE, allowing for a more luxurious lifestyle or more flexibility in retirement. This calculator helps you estimate your target portfolio size and track your progress toward that goal.
How it Works: The Math Behind FIRE
The core of early retirement planning, including Fat FIRE, relies on two main concepts:
Target Portfolio Size: This is the total amount of money you need saved to be financially independent. It's calculated by dividing your desired annual spending in retirement by your chosen Safe Withdrawal Rate (SWR).
For example, if you want to spend $80,000 per year and use a 4% SWR, your target portfolio is $80,000 / 0.04 = $2,000,000. The "Fat" aspect comes from choosing a higher annual spending figure.
Future Value of Savings: This calculator also estimates how your current savings, future contributions, and investment growth will shape your portfolio over time until retirement. The formula used is a future value of an annuity calculation, considering compound interest:
FV = PV * (1 + r)^n + P * [((1 + r)^n - 1) / r]
Where:
FV = Future Value
PV = Present Value (Current Savings)
r = Annual Investment Growth Rate (as a decimal)
n = Number of Years until Retirement
P = Annual Contributions (new savings)
This formula projects your portfolio's growth, assuming consistent contributions and average growth rates.
Key Inputs Explained:
Current Retirement Savings: The total amount you have already saved and invested for retirement.
Desired Annual Spending: The amount you estimate you'll need each year to live comfortably in retirement. This is the key differentiator for "Fat" FIRE, as it's typically higher than standard FIRE goals.
Safe Withdrawal Rate (SWR): The percentage of your portfolio you can safely withdraw each year without running out of money. The 4% rule is a common guideline, but lower rates (3-3.5%) offer more security, especially for longer retirements or higher spending. Higher SWRs increase risk.
Assumed Annual Investment Growth Rate: The average annual return you expect from your investments. This is a crucial assumption; be realistic and consider market volatility.
Annual Contributions: The total amount you plan to save and invest each year leading up to retirement. This significantly impacts how quickly you reach your goal. If you are already retired, set this to 0.
Years Until Retirement: The timeframe you have to reach your target.
Using the Calculator:
Enter your current financial details and retirement goals into the fields above. The calculator will provide:
Your Target Portfolio Size: The total amount needed based on your desired spending and SWR.
Projected Portfolio Value: An estimate of your portfolio's value at retirement based on your current savings, planned contributions, and assumed growth.
Progress Towards Goal: A comparison showing how your projected value stacks up against your target.
Adjust the inputs (especially withdrawal rate and contributions) to see how they impact your timeline and required savings. This tool is an estimate; actual results will vary based on market performance, inflation, and spending changes.
function calculateFatFire() {
var currentSavings = parseFloat(document.getElementById("currentSavings").value);
var annualSpending = parseFloat(document.getElementById("annualSpending").value);
var withdrawalRate = parseFloat(document.getElementById("withdrawalRate").value);
var investmentGrowthRate = parseFloat(document.getElementById("investmentGrowthRate").value);
var annualContributions = parseFloat(document.getElementById("annualContributions").value);
var yearsToRetirement = parseFloat(document.getElementById("yearsToRetirement").value);
var resultDiv = document.getElementById("result-value");
var progressInfoDiv = document.getElementById("progress-info");
resultDiv.innerHTML = ""; // Clear previous results
progressInfoDiv.innerHTML = "";
// Validate inputs
if (isNaN(currentSavings) || isNaN(annualSpending) || isNaN(withdrawalRate) || isNaN(investmentGrowthRate) || isNaN(annualContributions) || isNaN(yearsToRetirement)) {
resultDiv.innerHTML = "Please enter valid numbers for all fields.";
return;
}
if (withdrawalRate 10) {
resultDiv.innerHTML = "Safe Withdrawal Rate must be between 1% and 10%.";
return;
}
if (investmentGrowthRate < 0) {
resultDiv.innerHTML = "Investment growth rate cannot be negative.";
return;
}
if (yearsToRetirement 0) {
// Future Value of a lump sum + Future Value of an annuity
projectedPortfolio = pv * Math.pow(1 + r, n) + p * ((Math.pow(1 + r, n) – 1) / r);
} else {
// If growth rate is 0, it's simpler: initial + total contributions
projectedPortfolio = pv + (p * n);
}
// Format results
var formattedTargetPortfolio = targetPortfolio.toLocaleString('en-US', { style: 'currency', currency: 'USD', minimumFractionDigits: 0, maximumFractionDigits: 0 });
var formattedProjectedPortfolio = projectedPortfolio.toLocaleString('en-US', { style: 'currency', currency: 'USD', minimumFractionDigits: 0, maximumFractionDigits: 0 });
resultDiv.innerHTML = formattedTargetPortfolio;
// Add progress information
var shortfall = targetPortfolio – projectedPortfolio;
var progressPercent = Math.min(100, (projectedPortfolio / targetPortfolio) * 100); // Cap at 100%
var progressHtml = "