Loan EMI Calculator and Payment Schedule Generator using PHP

An Equated Monthly Installment (EMI) is defined as “A fixed payment amount made by a borrower to a lender at a specified date each calendar month. Equated monthly installments are used to pay off both interest and principal each month, so that over a specified number of years, the loan is fully paid off along with interest.”

The benefit of an EMI for borrowers is that they know precisely how much money they will need to pay toward their loan each month, making the personal budgeting process easier.

Source Code :

index.php
functions.php

index.php

<?php include_once('functions.php');?>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/5.1.0/css/bootstrap.min.css">

<style type="text/css">
  body{
    background-color: #a8d8cd;
  }
  .container{
    margin-top:30px;
  }
  .box{
    background-color: aliceblue;
    padding:30px;
    margin-bottom:20px;
  }
  .form-group{
    margin-bottom:20px;
    margin-top:20px;
  }
</style>

<?php
  if(isset($_POST['amount'])){
    $_POST['amount'] = str_replace(',','',$_POST['amount']);
    $emi = PMT($_POST['interest'],$_POST['period'],$_POST['amount']);
    $balance = $_POST['amount'];
    $payment_date = $_POST['start_date'];
  }
?>

<div class="container">
  <h1 class="text-center">Loan EMI Calculator and Schedule Generator</h1>
  <hr>
  <div class="box">
    <h3 class="text-center">Loan Details</h3>
    <hr>
    <form action="" method="post">
      <div class="row">
        <div class="col-6">
          <div class="form-group">
            <label>Loan Amount</label>
            <input type="text" name="amount" class="form-control" value="<?php echo number_format(@$_POST['amount'],0);?>" required>
          </div>
          <div class="form-group">
            <label>Interest (%)</label>
            <input type="text" name="interest" class="form-control" value="<?php echo @$_POST['interest'];?>" required>
          </div>
        </div>
        <div class="col-6">
          <div class="form-group">
            <label>Period (Years)</label>
            <input type="text" name="period" class="form-control" value="<?php echo @$_POST['period'];?>" required>
          </div>
          <div class="form-group">
            <label>Start Date</label>
            <input type="date" name="start_date" value="<?php echo @$_POST['start_date'];?>" class="form-control" required>
          </div>
        </div>
      </div>
      <input type="submit" class="btn btn-primary" value="Calculate">
    </form>
  </div>

  <div class="box">
    <div class="row">
      <div class="col-12">
        <div class="alert alert-info" role="alert">
          Monthly EMI Payment for the loan details amounts to <?php echo showValue($emi);?>
        </div>
        <h3 class="text-center">EMI Schedule</h3>
        <hr>
        <table class="table table-striped table-bordered">
          <thead>
            <tr>
              <th>SN</th>
              <th>Payment Date</th>
              <th>Monthly EMI</th>
              <th>Interest Paid</th>
              <th>Principal Paid</th>
              <th>Balance</th>
            </tr>
          </thead>
          <tbody>
            <?php for($i=1;$i<=$_POST['period']*12;$i++){?>
              <?php 
                $interest = (($_POST['interest']/100)*$balance)/12;
                $principal = $emi - $interest;
                $balance = $balance - $principal;
                $payment_date = date('Y-m-d',strtotime("+1 month",strtotime($payment_date)));
              ?>
              <tr>
                <td><?php echo $i;?></td>
                <td><?php showDate($payment_date);?></td>
                <td><?php showValue($emi);?></td>
                <td><?php showValue($interest);?></td>
                <td><?php showValue($principal);?></td>
                <td><?php showValue($balance);?></td>
              </tr>
            <?php } ?>
          </tbody>
        </table>
      </div>
    </div>
  </div>

</div>

functions.php

<?php

function PMT($interest,$period,$loan_amount){
  $interest = (float)$interest;
  $period = (float)$period;
  $loan_amount = (float)$loan_amount;
  $period = $period * 12;
  $interest = $interest / 1200;
  $amount = $interest * -$loan_amount * pow((1+$interest),$period) / (1 - pow((1+$interest), $period));
  return $amount;
}

function showValue($value){
  echo number_format($value,2);
}

function showDate($date){
  echo date('jS F, Y',strtotime($date));
}