function calculate() {

    let amount = parseFloat(document.getElementById("amount").value);
    let rate = parseFloat(document.getElementById("rate").value);

    let start = new Date(document.getElementById("start").value);
    let end = new Date(document.getElementById("end").value);

    if (isNaN(amount) || isNaN(rate)) {
        alert("Please Enter Amount & Interest Rate");
        return;
    }

    if (end < start) {
        alert("End Date must be greater than Start Date");
        return;
    }

    // Total Days
    let totalDays = Math.floor((end - start) / (1000 * 60 * 60 * 24));

    // Months & Days
    let months = Math.floor(totalDays / 30);
    let days = totalDays % 30;

    // Monthly Interest
    let monthInterest = (amount * rate / 100) * months;

    // Daily Interest
    let dayInterest = ((amount * rate / 100) / 30) * days;

    let interest = monthInterest + dayInterest;
    let total = amount + interest;

    document.getElementById("months").innerHTML = months;
    document.getElementById("days").innerHTML = days;
    document.getElementById("interest").innerHTML = "₹" + interest.toFixed(2);
    document.getElementById("total").innerHTML = "₹" + total.toFixed(2);

    saveHistory({
        amount,
        rate,
        months,
        days,
        interest,
        total
    });
}