.mpr-calculator-container {
max-width: 600px;
margin: 20px auto;
padding: 20px;
background: #f9f9f9;
border: 1px solid #ddd;
border-radius: 8px;
font-family: Arial, sans-serif;
}
.mpr-calculator-container h3 {
text-align: center;
margin-bottom: 20px;
color: #333;
}
.mpr-form-group {
margin-bottom: 15px;
}
.mpr-form-group label {
display: block;
margin-bottom: 5px;
font-weight: bold;
color: #555;
}
.mpr-form-group input {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
box-sizing: border-box;
font-size: 16px;
}
.mpr-btn {
width: 100%;
padding: 12px;
background-color: #007bff;
color: white;
border: none;
border-radius: 4px;
font-size: 16px;
cursor: pointer;
transition: background-color 0.3s;
}
.mpr-btn:hover {
background-color: #0056b3;
}
.mpr-result {
margin-top: 20px;
padding: 15px;
background: #e9ecef;
border-radius: 4px;
display: none;
}
.mpr-result h4 {
margin-top: 0;
color: #333;
border-bottom: 1px solid #ccc;
padding-bottom: 10px;
}
.mpr-result-item {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
font-size: 15px;
}
.mpr-result-value {
font-weight: bold;
color: #28a745;
}
.mpr-article {
max-width: 800px;
margin: 40px auto;
font-family: Arial, sans-serif;
line-height: 1.6;
color: #333;
}
.mpr-article h2 {
color: #007bff;
margin-top: 30px;
}
.mpr-article p {
margin-bottom: 15px;
}
.mpr-article ul {
margin-bottom: 15px;
}
function calculateMPR() {
var aprInput = document.getElementById('annualRate').value;
var balanceInput = document.getElementById('principalBalance').value;
var resultDiv = document.getElementById('mprResult');
// Validation
if (aprInput === "" || isNaN(aprInput)) {
alert("Please enter a valid Annual Percentage Rate.");
return;
}
var apr = parseFloat(aprInput);
var balance = (balanceInput === "" || isNaN(balanceInput)) ? 0 : parseFloat(balanceInput);
// Core Calculations
// 1. Calculate Monthly Percentage Rate (MPR)
// Formula: APR / 12
var mpr = apr / 12;
// 2. Calculate Daily Percentage Rate (DPR)
// Formula: APR / 365
var dpr = apr / 365;
// 3. Calculate Monthly Interest Amount based on Balance
// Formula: Balance * (MPR / 100)
var monthlyInterest = balance * (mpr / 100);
// Update DOM
document.getElementById('displayMPR').innerText = mpr.toFixed(4) + "%";
document.getElementById('displayDPR').innerText = dpr.toFixed(4) + "%";
// Format currency logic
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
});
document.getElementById('displayInterest').innerText = formatter.format(monthlyInterest);
// Show result box
resultDiv.style.display = "block";
}
Understanding the Monthly Percentage Rate (MPR)
The Monthly Percentage Rate (MPR) is a crucial metric often overlooked by consumers who focus solely on the Annual Percentage Rate (APR). While APR gives you a broad view of the cost of borrowing over a year, the MPR tells you exactly how much interest is accruing on your balance every single month. This is particularly important for revolving credit lines, such as credit cards, where interest is calculated frequently.
How the Monthly Percentage Rate Calculator Works
This calculator converts your annual rate into a periodic monthly rate. Financial institutions typically calculate interest by dividing your APR by the number of periods in a year.
- APR Input: The yearly interest rate quoted by your lender or credit card issuer.
- MPR Output: Derived by dividing the APR by 12 (months in a year).
- Interest Cost: By inputting your current balance, the calculator applies the MPR to estimate the actual dollar amount you will be charged in interest for that billing cycle.
Formula for Monthly Percentage Rate
The math behind converting APR to MPR is relatively standard across most credit card agreements. The formula used is:
MPR = APR / 12
For example, if you have a credit card with an APR of 24%:
24% / 12 = 2% per month.
This means if you carry a balance of $1,000, you are charged 2% of that balance ($20) in interest for that month alone.
Daily Percentage Rate (DPR)
Some issuers calculate interest based on a Daily Percentage Rate (DPR) and multiply it by the number of days in the billing cycle. The calculator above also provides this figure by dividing the APR by 365. This offers a more granular view of how interest accumulates daily on your average daily balance.
Why MPR Matters
Understanding your MPR allows you to verify your credit card statements and better strategize your debt repayment. Because interest compounds, knowing the monthly rate helps you understand why minimum payments often barely cover the interest charges, leaving the principal balance largely untouched. By using this calculator, you can forecast your monthly interest costs and adjust your payment strategy to reduce debt faster.