Please enter valid positive numbers for all fields.
Total Savings at Retirement
$0.00
This is your estimated nest egg.
Estimated Monthly Income
$0.00
Based on a safe 4% annual withdrawal rate.
Total Interest Earned
$0.00
Money your money made for you.
function calculateRetirement() {
// Get input values
var currentAge = document.getElementById('currentAge').value;
var retireAge = document.getElementById('retireAge').value;
var currentSavings = document.getElementById('currentSavings').value;
var monthlyContribution = document.getElementById('monthlyContribution').value;
var annualReturn = document.getElementById('annualReturn').value;
// DOM elements for results
var resultsDiv = document.getElementById('results');
var errorMsg = document.getElementById('errorMsg');
var totalSavingsEl = document.getElementById('totalSavings');
var monthlyIncomeEl = document.getElementById('monthlyIncome');
var totalInterestEl = document.getElementById('totalInterest');
// Reset display
resultsDiv.style.display = 'none';
errorMsg.style.display = 'none';
// Validate inputs
if (currentAge === " || retireAge === " || currentSavings === " || monthlyContribution === " || annualReturn === ") {
errorMsg.innerText = "Please fill in all fields.";
errorMsg.style.display = 'block';
return;
}
var ageStart = parseFloat(currentAge);
var ageEnd = parseFloat(retireAge);
var startBalance = parseFloat(currentSavings);
var monthlyAdd = parseFloat(monthlyContribution);
var rate = parseFloat(annualReturn);
if (isNaN(ageStart) || isNaN(ageEnd) || isNaN(startBalance) || isNaN(monthlyAdd) || isNaN(rate)) {
errorMsg.innerText = "Please ensure all values are valid numbers.";
errorMsg.style.display = 'block';
return;
}
if (ageStart >= ageEnd) {
errorMsg.innerText = "Retirement age must be greater than current age.";
errorMsg.style.display = 'block';
return;
}
// Calculation Logic
var years = ageEnd – ageStart;
var months = years * 12;
var monthlyRate = (rate / 100) / 12;
var futureValue = 0;
var totalPrincipal = startBalance + (monthlyAdd * months);
if (rate === 0) {
futureValue = totalPrincipal;
} else {
// Compound interest for initial principal
var fvPrincipal = startBalance * Math.pow(1 + monthlyRate, months);
// Future value of a series (monthly contributions)
// PMT * [((1 + r)^n – 1) / r]
var fvSeries = monthlyAdd * (Math.pow(1 + monthlyRate, months) – 1) / monthlyRate;
futureValue = fvPrincipal + fvSeries;
}
var interestEarned = futureValue – totalPrincipal;
// 4% Rule for monthly income: (Total * 0.04) / 12
var safeMonthlyIncome = (futureValue * 0.04) / 12;
// Formatting currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 0,
maximumFractionDigits: 0,
});
// Update DOM
totalSavingsEl.innerText = formatter.format(futureValue);
monthlyIncomeEl.innerText = formatter.format(safeMonthlyIncome);
totalInterestEl.innerText = formatter.format(interestEarned);
resultsDiv.style.display = 'block';
}
Retirement Planning Guide: Securing Your Future
Planning for retirement is one of the most significant financial tasks you will undertake. Using a Retirement Savings Calculator helps you visualize whether your current savings habits align with your future lifestyle goals. Understanding the math behind your nest egg is the first step toward financial freedom.
How This Calculator Works
Our tool uses the standard compound interest formula to project your wealth growth over time. It takes into account three main levers of wealth building:
Time Horizon: The number of years between your current age and your planned retirement age.
Contributions: The amount of money you add to your investment accounts monthly.
Rate of Return: The annual percentage growth of your investments (compounded monthly).
We also calculate an estimated "Monthly Income" based on the popular 4% Rule. This financial rule of thumb suggests that you can withdraw 4% of your total portfolio in the first year of retirement (adjusted for inflation thereafter) without running out of money for at least 30 years.
Why Starting Early Matters
The variable that has the biggest impact on your final number is often not the amount you save, but when you start saving. This is due to the exponential nature of compound interest. Money invested in your 20s has decades to double and redouble. If you start later, you will need to contribute significantly more monthly capital to achieve the same result.
Understanding the 4% Rule
The "Estimated Monthly Income" displayed in the results assumes a safe withdrawal rate of 4%. This is a standard benchmark used by financial planners.
The Goal: To keep your principal intact or depleting very slowly so it lasts through your retirement.
The Risk: Withdrawing too much too soon can increase the risk of "sequence of returns risk"—where a market downturn early in retirement depletes your portfolio faster than it can recover.
Factors Affecting Your Return
While this calculator assumes a fixed annual return (e.g., 7%), real market returns fluctuate. The S&P 500 has historically returned about 10% annually on average before inflation. When planning, it is often wise to use a conservative estimate (between 6% and 8%) to account for inflation and market volatility.
Remember, this calculator provides an estimate. Your actual retirement needs will depend on your lifestyle, healthcare costs, tax situation, and other sources of income like Social Security or pensions.