Calculate the future value of your periodic investments and principal sums.
Monthly
Quarterly
Annually
End of Period (Ordinary)
Beginning of Period (Due)
Projection Summary
Total Accumulated Balance
0.00
Total Contributions
0.00
Total Growth Accrued
0.00
Note: This calculation assumes a fixed growth percentage compounded at the same frequency as contributions. Actual financial results may vary based on market fluctuations.
Understanding Annuity Calculations
An annuity is a sequence of equal payments made at regular intervals. This tool helps you visualize how wealth accumulates over time through the power of compounding and consistent contributions. Whether you are planning for retirement or a long-term savings goal, understanding the future value of an annuity is essential.
Key Variables in Your Projection
Starting Principal: The initial lump sum you possess before making any periodic contributions.
Annual Yield Percentage: The expected average growth rate per year. Even small changes in this percentage can significantly impact long-term results.
Annuity Type: An Ordinary Annuity assumes payments are made at the end of each month or year. An Annuity Due assumes payments are made at the beginning, allowing for an extra period of growth.
The Math Behind the Growth
The calculation uses the Future Value of an Annuity formula. For an ordinary annuity, the formula is:
FV = P × [((1 + r)^n – 1) / r]
Where P is the periodic payment, r is the yield rate per period, and n is the total number of periods. If you have a starting principal, we also calculate its compound growth separately using A = PV(1 + r)^n and add it to the annuity total.
Practical Example
Imagine you start with 10,000 and contribute 500 every month for 15 years with an annual yield of 6%.
As an Ordinary Annuity, your total balance would grow to approximately 170,165. In this scenario, your total contributions would be 90,000 (plus the 10,000 initial sum), meaning you earned over 70,000 just from growth.
function calculateAnnuity() {
var principal = parseFloat(document.getElementById("principalAmount").value);
var pmt = parseFloat(document.getElementById("periodicPayment").value);
var annualRate = parseFloat(document.getElementById("annualYield").value) / 100;
var years = parseFloat(document.getElementById("horizonYears").value);
var freq = parseInt(document.getElementById("frequency").value);
var type = parseInt(document.getElementById("annuityType").value);
// Basic Validation
if (isNaN(principal) || isNaN(pmt) || isNaN(annualRate) || isNaN(years)) {
alert("Please ensure all fields are filled with valid numerical values.");
return;
}
// Periodic rate and total periods
var r = annualRate / freq;
var n = years * freq;
var fv_annuity = 0;
var fv_principal = 0;
// Calculation for Principal Compound Growth
if (r === 0) {
fv_principal = principal;
} else {
fv_principal = principal * Math.pow((1 + r), n);
}
// Calculation for Annuity Payments
if (r === 0) {
fv_annuity = pmt * n;
} else {
fv_annuity = pmt * ((Math.pow((1 + r), n) – 1) / r);
// Adjust for Annuity Due (Beginning of period)
if (type === 1) {
fv_annuity = fv_annuity * (1 + r);
}
}
var totalFV = fv_principal + fv_annuity;
var totalInvested = principal + (pmt * n);
var totalGrowth = totalFV – totalInvested;
// Formatter for Currency style (without the symbol to strictly follow instructions where requested)
function formatVal(val) {
return val.toLocaleString(undefined, { minimumFractionDigits: 2, maximumFractionDigits: 2 });
}
document.getElementById("totalBalance").innerHTML = formatVal(totalFV);
document.getElementById("totalContributions").innerHTML = formatVal(totalInvested);
document.getElementById("totalGrowth").innerHTML = formatVal(totalGrowth);
}
// Initial calculation on load
window.onload = function() {
calculateAnnuity();
};