Calculating future value with compound interest wi

I'm trying to work on a script where the user inserts a monthly income and gets the future value with compound interest after 30 years. As it is now, I've assigned some values for testing purposes.

// Future Value
var investment = 800;
var annualRate = 2;
var monthlyRate = annualRate / 12 / 100;
var years = 30;
var months = years * 12;
var futureValue = 0;

for ( i = 1; i <= months; i++ ) {
    futureValue = futureValue + investment * Math.pow(1 + monthlyRate, months);
}

Problem is, I'm actually building this from an Excel spreadsheet that's using the built-in FV() formula and when cross checking, my results are totally off... Any idea what I'm doing wrong since I'm not into finance math at all. Thanks in advance.

标签： javascript finance

5条回答

女痞

2楼-- · 2020-05-24 06:51

Also I found with this alternative:

function compoundInterest(principal, annual_rate, n_times, t_years) {
    return principal*(Math.pow(1 + annual_rate/n_times, n_times*t_years) - 1);
}

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够拽才男人

3楼-- · 2020-05-24 06:58

function FVcalc(PresentAmount,InterestRate,NumberOfYears) {
    var timescompound = 1;
    var AnnualInterestRate = (InterestRate/100)/timescompound;
    var Years= NumberOfYears

    var Periods=timescompound*Years;
    var NumPayments=Periods;
    var Prin=PresentAmount;

    MonthPayment=Math.floor((Prin)*(Math.pow((1+AnnualInterestRate),(Periods)))*100)/100;
    FVFactor=(Math.pow((1+AnnualInterestRate),(Periods)))
    return MonthPayment
}

http://www.uic.edu/classes/actg/actg500/pfvatutor.htm

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forever°为你锁心

4楼-- · 2020-05-24 06:59

This is my way of writing code for compound interest

function call()
    {
        var A = Principle;
        var B = Interest;
        var C = Years;
        var D = 0;
        var E = A*B/100;
        D+=E;
        var f=E+A;
        document.write("0 year: Interest "+E+" Principal: "+f);
        document.write("<br />");
        for (var i=1; i<C; i++)
        {
            E=f*B/100;
            D+=E;
            f=E+f;
            document.write(i+"year: Interest "+E+" Principal:"+f);
            document.write("<br />");
        }

    return false;
    }

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做个烂人

5楼-- · 2020-05-24 07:12

The Math.pow is unnecessary, since you are calculating and incrementing futureValue month by month. Simply multiply by 1 + monthlyRate. You also want to add the current value of the investment to the new investment before multiplying:

for ( i = 1; i <= months; i++ ) {
   futureValue = (futureValue + investment) * (1 + monthlyRate);
}

Alternatively, you can also calculate this in one go with the following formula:

futureValue = investment * (Math.pow(1 + monthlyRate, months) - 1) / monthlyRate;

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霸刀☆藐视天下

6楼-- · 2020-05-24 07:13

Below is the code to calculate compound interest.

function calculate() {
  p = document.getElementById("p").value;
  n = document.getElementById("n").value; // no. of compoundings per year
  t = document.getElementById("t").value; // no. of years
  r = document.getElementById("r").value;
  result = document.getElementById("result");

  // The equation is A = p * [[1 + (r/n)] ^ nt]
  A = (p * Math.pow((1 + (r / (n * 100))), (n * t)));

  // toFixed is used for rounding the amount with two decimal places.
  result.innerHTML = "The total amount is " + A.toFixed(2);

  result.innerHTML += "<br> The interest is " + (A.toFixed(2) - p).toFixed(2);
}

div {
  display: table-row;
}

label,
input {
  display: table-cell;
}

<html>

<head>
  <title>Compound Interest Calculation using jQuery</title>
</head>
<body>
  <h1>Compound Interest Calculation Using jQuery</h1>
  <div> <label>Amount: </label> <input id="p"> </div>
  <div> <label>Rate (%): </label> <input id="r"> </div>
  <div> <label>No. of Years: </label> <input id="t"> </div>
  <div> <label>Compunding Times Per Year: </label> <input id="n" value="1"> </div>

  <button onclick="calculate()">Calculate</button>

  <p id="result"></p>
</body>

</html>

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Calculating future value with compound interest wi

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