Coast Fire Calculator

Coast FIRE Calculator

Use this calculator to determine your Coast FIRE number – the amount you need to have saved today so that, without any further contributions, your investments will grow to your full financial independence (FI) number by your target retirement age.

function calculateCoastFIRE() { var currentInvestments = parseFloat(document.getElementById('currentInvestments').value); var annualSpending = parseFloat(document.getElementById('annualSpending').value); var growthRate = parseFloat(document.getElementById('growthRate').value) / 100; var currentAge = parseInt(document.getElementById('currentAge').value); var targetRetirementAge = parseInt(document.getElementById('targetRetirementAge').value); var resultsDiv = document.getElementById('coastFireResults'); resultsDiv.innerHTML = "; // Clear previous results if (isNaN(currentInvestments) || isNaN(annualSpending) || isNaN(growthRate) || isNaN(currentAge) || isNaN(targetRetirementAge) || currentInvestments < 0 || annualSpending <= 0 || growthRate < 0 || currentAge < 18 || targetRetirementAge <= currentAge) { resultsDiv.innerHTML = 'Please enter valid positive numbers for all fields. Target Retirement Age must be greater than Current Age.'; return; } var yearsToGrow = targetRetirementAge – currentAge; // Calculate Full FI Number (using 4% rule, 25x annual spending) var fullFINumber = annualSpending * 25; // Calculate Coast FIRE Number (Present Value needed to reach Full FI Number) var coastFINumber = fullFINumber / Math.pow((1 + growthRate), yearsToGrow); // Projected growth of current investments var projectedFIWithCurrentSavings = currentInvestments * Math.pow((1 + growthRate), yearsToGrow); var outputHTML = '

Your Coast FIRE Results:

'; outputHTML += 'Desired Full FI Number: $' + fullFINumber.toLocaleString('en-US', { minimumFractionDigits: 0, maximumFractionDigits: 0 }) + "; outputHTML += 'This is the total amount you aim to have saved by age ' + targetRetirementAge + ' to cover your desired annual spending of $' + annualSpending.toLocaleString('en-US', { minimumFractionDigits: 0, maximumFractionDigits: 0 }) + ' (based on the 4% rule).'; outputHTML += 'Your Coast FIRE Number: $' + coastFINumber.toLocaleString('en-US', { minimumFractionDigits: 0, maximumFractionDigits: 0 }) + "; outputHTML += 'This is the amount you need to have saved today (' + currentAge + ' years old) so that, if left untouched to grow at ' + (growthRate * 100).toFixed(1) + '% annually, it will reach your Full FI Number by age ' + targetRetirementAge + '.'; if (currentInvestments >= coastFINumber) { var surplus = currentInvestments – coastFINumber; outputHTML += 'Congratulations! You have already reached your Coast FIRE number. You have a surplus of $' + surplus.toLocaleString('en-US', { minimumFractionDigits: 0, maximumFractionDigits: 0 }) + '.'; outputHTML += 'If you stop contributing now, your current investments of $' + currentInvestments.toLocaleString('en-US', { minimumFractionDigits: 0, maximumFractionDigits: 0 }) + ' are projected to grow to approximately $' + projectedFIWithCurrentSavings.toLocaleString('en-US', { minimumFractionDigits: 0, maximumFractionDigits: 0 }) + ' by age ' + targetRetirementAge + ', exceeding your desired Full FI Number.'; } else { var deficit = coastFINumber – currentInvestments; outputHTML += 'You need to save an additional $' + deficit.toLocaleString('en-US', { minimumFractionDigits: 0, maximumFractionDigits: 0 }) + ' to reach your Coast FIRE number.'; outputHTML += 'If you stop contributing now, your current investments of $' + currentInvestments.toLocaleString('en-US', { minimumFractionDigits: 0, maximumFractionDigits: 0 }) + ' are projected to grow to approximately $' + projectedFIWithCurrentSavings.toLocaleString('en-US', { minimumFractionDigits: 0, maximumFractionDigits: 0 }) + ' by age ' + targetRetirementAge + ', which is less than your desired Full FI Number.'; } resultsDiv.innerHTML = outputHTML; } .coast-fire-calculator { font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; background-color: #f9f9f9; padding: 25px; border-radius: 10px; box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1); max-width: 700px; margin: 30px auto; border: 1px solid #e0e0e0; } .coast-fire-calculator h2 { color: #2c3e50; text-align: center; margin-bottom: 20px; font-size: 28px; } .coast-fire-calculator p { color: #34495e; line-height: 1.6; margin-bottom: 15px; } .calculator-inputs label { display: block; margin-bottom: 8px; font-weight: bold; color: #34495e; font-size: 15px; } .calculator-inputs input[type="number"] { width: calc(100% – 22px); padding: 12px; margin-bottom: 18px; border: 1px solid #ccc; border-radius: 6px; font-size: 16px; box-sizing: border-box; transition: border-color 0.3s ease; } .calculator-inputs input[type="number"]:focus { border-color: #007bff; outline: none; box-shadow: 0 0 5px rgba(0, 123, 255, 0.3); } .calculator-inputs button { background-color: #28a745; color: white; padding: 14px 25px; border: none; border-radius: 6px; cursor: pointer; font-size: 18px; font-weight: bold; display: block; width: 100%; margin-top: 20px; transition: background-color 0.3s ease, transform 0.2s ease; } .calculator-inputs button:hover { background-color: #218838; transform: translateY(-2px); } .calculator-results { margin-top: 30px; padding: 20px; background-color: #e9f7ef; border: 1px solid #d4edda; border-radius: 8px; color: #155724; } .calculator-results h3 { color: #2c3e50; margin-top: 0; margin-bottom: 15px; font-size: 24px; text-align: center; } .calculator-results p { font-size: 16px; margin-bottom: 10px; } .calculator-results p strong { color: #000; } .calculator-results p.error { color: #dc3545; font-weight: bold; }

Understanding Coast FIRE

Coast FIRE is a financial independence strategy where you save and invest a significant amount of money early in your career. Once you hit your "Coast FIRE number," you stop making new contributions to your retirement accounts. You then let that initial sum grow untouched, relying on compound interest to reach your full financial independence (FI) goal by your traditional retirement age.

How Coast FIRE Works

The core idea behind Coast FIRE is leveraging the power of compound interest over a long period. By front-loading your savings, you give your money decades to grow. This strategy can offer immense flexibility:

• Reduced Pressure: After hitting your Coast FIRE number, you no longer need to contribute to retirement. This can free you up to pursue lower-paying but more fulfilling work, take a sabbatical, or work part-time.
• Early Financial Security: Even if you don't fully retire early, knowing your retirement is "covered" can significantly reduce financial stress.
• Flexibility: It allows you to downshift your career without jeopardizing your long-term financial goals.

Key Components of the Calculator

• Current Retirement Investments: This is the total amount you currently have saved in investment accounts (e.g., 401k, IRA, brokerage accounts) that are intended for retirement.
• Desired Annual Spending in Retirement: This is your estimated annual expenses once you are fully retired. A common rule of thumb for financial independence is to save 25 times this amount (the "4% rule").
• Expected Annual Growth Rate: This is the average annual return you anticipate your investments will generate. A common assumption for long-term diversified portfolios, adjusted for inflation, is 5-7%.
• Current Age: Your age today.
• Target Retirement Age: The age at which you plan to fully retire and begin drawing from your investments.

Example Scenario

Let's say you are 30 years old with $100,000 saved. You want to retire at 60 and believe you'll need $50,000 per year in retirement. Assuming a 7% annual growth rate:

1. Desired Full FI Number: $50,000 (annual spending) * 25 = $1,250,000.
2. Years to Grow: 60 (target age) – 30 (current age) = 30 years.
3. Coast FIRE Number: To reach $1,250,000 in 30 years with a 7% growth rate, you would need approximately $164,214 today.
4. Your Status: Since you only have $100,000, you would need to save an additional $64,214 to hit your Coast FIRE number. If you stopped contributing now, your $100,000 would only grow to about $761,200 by age 60, falling short of your $1,250,000 goal.

This calculator helps you understand if you're on track or how much more you need to save to achieve this powerful financial milestone.