function calculateBalanceTransfer() {
var bal = parseFloat(document.getElementById('currentBalance').value);
var curAPR = parseFloat(document.getElementById('currentAPR').value) / 100;
var newAPR = parseFloat(document.getElementById('newAPR').value) / 100;
var duration = parseInt(document.getElementById('promoDuration').value);
var feeRate = parseFloat(document.getElementById('transferFeePercent').value) / 100;
var monthlyPay = parseFloat(document.getElementById('monthlyPayment').value);
if (isNaN(bal) || isNaN(curAPR) || isNaN(newAPR) || isNaN(duration) || isNaN(feeRate) || isNaN(monthlyPay)) {
alert("Please fill in all fields with valid numbers.");
return;
}
if (monthlyPay <= (bal * (curAPR / 12))) {
alert("Monthly payment must be higher than the interest charged on the current card.");
return;
}
// 1. Calculate Transfer Fee
var totalFee = bal * feeRate;
var startingNewBal = bal + totalFee;
// 2. Calculate interest on OLD card for the duration of the promo
var oldInterestPaid = 0;
var tempBalOld = bal;
for (var i = 0; i < duration; i++) {
var monthlyInterest = tempBalOld * (curAPR / 12);
oldInterestPaid += monthlyInterest;
tempBalOld = tempBalOld + monthlyInterest – monthlyPay;
if (tempBalOld <= 0) break;
}
// 3. Calculate interest on NEW card for the duration of the promo
var newInterestPaid = 0;
var tempBalNew = startingNewBal;
for (var j = 0; j < duration; j++) {
var monthlyInterestNew = tempBalNew * (newAPR / 12);
newInterestPaid += monthlyInterestNew;
tempBalNew = tempBalNew + monthlyInterestNew – monthlyPay;
if (tempBalNew <= 0) break;
}
var netSavingsVal = oldInterestPaid – (newInterestPaid + totalFee);
// Display results
document.getElementById('feeResult').innerText = '$' + totalFee.toFixed(2);
document.getElementById('interestSaved').innerText = '$' + (oldInterestPaid – newInterestPaid).toFixed(2);
document.getElementById('netSavings').innerText = '$' + netSavingsVal.toFixed(2);
var summary = "By transferring your balance, you pay an upfront fee of $" + totalFee.toFixed(2) +
", but you avoid paying approximately $" + oldInterestPaid.toFixed(2) +
" in interest on your current card over the next " + duration + " months.";
document.getElementById('summaryText').innerText = summary;
document.getElementById('resultArea').style.display = 'block';
}
How a Balance Transfer Calculator Helps You Save
A credit card balance transfer can be a powerful financial tool for debt reduction. This strategy involves moving debt from a high-interest credit card to a new card with a lower introductory rate, often 0% APR. Our calculator helps you determine if the transfer fee is worth the potential interest savings.
Key Metrics Defined
Current Debt Balance: The total amount you currently owe on your high-interest credit card.
Transfer Fee: Most banks charge a one-time fee to move your balance, typically ranging from 3% to 5% of the total amount transferred.
Intro Period: The number of months the low or 0% APR is guaranteed (commonly 12 to 21 months).
Net Savings: The total interest you avoid paying minus the cost of the transfer fee.
Realistic Example of Savings
Imagine you have a $5,000 balance on a card with a 20% APR. If you pay $300 per month, you would pay hundreds of dollars in interest over the next year.
By transferring that balance to a 0% APR card for 15 months with a 3% fee:
Upfront Fee: $150 (3% of $5,000)
Interest Paid on Old Card: ~$650 over 15 months.
Net Savings: $500 ($650 saved – $150 fee).
Strategic Tips for Success
To maximize the benefit of a balance transfer, aim to pay off the entire balance before the introductory period expires. If a balance remains after the promo ends, the interest rate will jump to the standard APR, which could negate your initial savings. Avoid making new purchases on the transfer card, as these may not be subject to the 0% rate and can make it harder to track your progress toward debt freedom.