function calculateCDReturns() {
var depositInput = document.getElementById("depositAmount").value;
var rateInput = document.getElementById("apyRate").value;
// Validation
if (depositInput === "" || rateInput === "") {
alert("Please enter both the Deposit Amount and the APY rate.");
return;
}
var principal = parseFloat(depositInput);
var apy = parseFloat(rateInput);
if (isNaN(principal) || principal < 0) {
alert("Please enter a valid positive deposit amount.");
return;
}
if (isNaN(apy) || apy < 0) {
alert("Please enter a valid positive APY percentage.");
return;
}
// Calculations
// Note: APY takes into account compounding frequency.
// For a 7-day CD, calculation usually assumes simple interest for the short term derived from the annual rate.
// Daily rate formula based on 365 day year standard for banking.
var annualInterest = principal * (apy / 100);
var dailyInterest = annualInterest / 365;
// 7-Day Term Logic
var interest7Days = dailyInterest * 7;
var totalBalance7Days = principal + interest7Days;
// Monthly Projection (30 days) if renewed
var interest30Days = dailyInterest * 30;
// Display Results with currency formatting
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2,
maximumFractionDigits: 2
});
document.getElementById("termInterest").innerHTML = formatter.format(interest7Days);
document.getElementById("termBalance").innerHTML = formatter.format(totalBalance7Days);
document.getElementById("monthlyProjection").innerHTML = formatter.format(interest30Days);
document.getElementById("annualProjection").innerHTML = formatter.format(annualInterest);
document.getElementById("results").style.display = "block";
}
Understanding Third Federal 7-Day CD Rates
Certificates of Deposit (CDs) are a cornerstone of conservative investment strategies, offering a fixed rate of return over a specified period. While most investors are familiar with 1-year or 5-year terms, institutions like Third Federal Savings and Loan typically offer specialized short-term products, such as the 7-Day CD. This calculator helps you determine exactly how much interest you will accrue over this short duration based on current APY offerings.
How a 7-Day CD Works
Unlike standard savings accounts where interest rates can fluctuate daily, a 7-day CD locks in an interest rate for exactly one week. At the end of the 7 days (the maturity date), you generally have a few options:
Renew: Allow the CD to automatically renew for another 7-day term at the current prevailing rate.
Withdraw: Cash out the principal and the accrued interest without penalty.
Add Funds: Increase the principal balance before the next 7-day term begins.
Tip: Short-term CDs like the 7-day option are excellent for "parking" cash that you might need access to in the near future, but want to earn a higher yield on than a standard checking account.
The Mathematics of 7-Day Interest
It is important to understand that the rate advertised is usually the APY (Annual Percentage Yield), not the yield you get in one week. The bank calculates the interest based on holding the money for a full year. To find your actual earnings for the 7-day period, the calculation logic used in the tool above follows this formula:
For example, if you deposit $50,000 at an APY of 4.00%:
Annual Earnings would be $2,000.
Daily Earnings would be roughly $5.48 ($2,000 / 365).
7-Day Earnings would be approximately $38.36.
Why Choose a Third Federal 7-Day CD?
Third Federal is known for competitive rates and stability. Their 7-day CD products are often used by retirees or investors who are waiting for better long-term rates or need liquidity for an upcoming purchase (like a home closing or tax payment). It provides a blend of liquidity (access to funds every Tuesday or specific maturity day) and yield.
Key Considerations
Minimum Deposit: Many 7-day CDs require a higher minimum deposit (often $500 or more) compared to standard savings accounts.
Taxes: Interest earned on CDs is considered taxable income by the IRS and must be reported.
Rate Fluctuations: Since the term is only 7 days, if you choose to renew, your rate for the next week will adjust to whatever the bank is offering at that time. It is not a long-term fixed rate.
Using the Calculator
To use the calculator above effectively:
Input Deposit: Enter the total amount of cash you intend to invest in the CD.
Input APY: Enter the current Annual Percentage Yield offered by Third Federal (check their official site for today's specific rate).
Calculate: Click the button to see your gross interest for the single 7-day term, as well as projections if you were to keep renewing at that rate for a month or year.