How Long Will My Savings Last Calculator

How Long Will My Savings Last?

Calculate the lifespan of your nest egg based on withdrawals and growth.

Your Results

Understanding Savings Longevity

Planning for retirement or a long career break requires understanding the "burn rate" of your capital. This calculator determines how many years and months your current savings will last given a specific monthly withdrawal, while accounting for both the growth of your investments and the eroding power of inflation.

Key Factors in the Calculation

• The Real Rate of Return: This is your investment return minus the inflation rate. If your investments return 7% but inflation is 3%, your purchasing power is only growing by 4%.
• Withdrawal Sustainability: If your monthly withdrawal is less than the interest generated by your balance, your money will theoretically last forever.
• Inflation Impact: This calculator adjusts your withdrawals upward each year to maintain the same purchasing power as your initial entry.

Example Scenario

Suppose you have 400,000 in savings. You plan to withdraw 2,000 per month. You expect a 6% annual return on your investments and anticipate 3% annual inflation. In this scenario, your real return is roughly 3%. Based on these figures, your savings would last approximately 24 years and 10 months.

function calculateLongevity() { var P = parseFloat(document.getElementById('currentBalance').value); var W = parseFloat(document.getElementById('monthlySpend').value); var annualReturn = parseFloat(document.getElementById('expectedReturn').value) / 100; var inflation = parseFloat(document.getElementById('inflationRate').value) / 100; var resultArea = document.getElementById('resultArea'); var resultOutput = document.getElementById('resultOutput'); var resultMessage = document.getElementById('resultMessage'); if (isNaN(P) || isNaN(W) || isNaN(annualReturn) || isNaN(inflation)) { alert("Please enter valid numbers in all fields."); return; } if (W 0 && (P * r) >= W) { resultArea.style.display = "block"; resultOutput.innerHTML = "Indefinite (Perpetual)"; resultMessage.innerHTML = "Your investment returns exceed your spending. Your balance will grow over time!"; return; } // Case for no growth (0% real return) if (Math.abs(r) < 0.000001) { months = P / W; } else { // Longevity formula: n = -log(1 – (P*r/W)) / log(1 + r) var numerator = 1 – (P * r / W); if (numerator = W) check, // but included for mathematical robustness. months = 1200; // 100+ years limit } else { months = -Math.log(numerator) / Math.log(1 + r); } } resultArea.style.display = "block"; if (months >= 1200) { resultOutput.innerHTML = "100+ Years"; resultMessage.innerHTML = "Based on these rates, your money is extremely sustainable."; } else { var totalYears = Math.floor(months / 12); var remainingMonths = Math.floor(months % 12); var yearText = totalYears === 1 ? "1 Year" : totalYears + " Years"; var monthText = remainingMonths === 1 ? "1 Month" : remainingMonths + " Months"; resultOutput.innerHTML = yearText + " and " + monthText; resultMessage.innerHTML = "This is when your balance is projected to reach zero, adjusted for inflation."; } }