stainer

<div class="calculator_table">
  <select id="calc-month">
    <option value="0">January</option>
    <option value="1">February</option>
    <option value="2">March</option>
    <option value="3">April</option>
    <option value="4">May</option>
    <option value="5">June</option>
    <option value="6">July</option>
    <option value="7">August</option>
    <option value="8">September</option>
    <option value="9">October</option>
    <option value="10">November</option>
    <option value="11">December</option>
  </select>

  <select id="calc-day"></select>
  <select id="calc-year"></select>

  <p align="center"><button onclick="calculate();return false;">Calculate</button></p>
  <div id="results"></div>
</div>

<script>
  window.onload = function() 
  {
	var npw = new Date();
	var g = npw.getFullYear();
	var m = npw.getMonth();
	var da = npw.getDate();
	
    for (var y = 2014; y < 2050; y++ )
    {
		document.getElementById('calc-year').innerHTML += '<option value="'+y+'">' + y +'</option>'; 	
    }

    for (var d = 1; d <= 31; d++ )
    {
      document.getElementById('calc-day').innerHTML += '<option value="'+d+'">' + d +'</option>'; 
    }
	document.getElementById('calc-year').value=g;
	document.getElementById('calc-month').value=m;
	document.getElementById('calc-day').value=da;
  }

  function calculate()
  {
    var monthNames = new Array('January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December');
    var day = Number(document.getElementById('calc-day').value);
    var month = Number(document.getElementById('calc-month').value);
    var year = Number(document.getElementById('calc-year').value);
    var nextday = day + 280;
    var initial = new Date(Date.UTC( year, month, day, 0, 0, 0));
    var predicted = new Date(Date.UTC( year, month, nextday, 0, 0, 0));
    var now = new Date();

    var formated = monthNames[predicted.getMonth()] + ' ' + predicted.getDate() + ', ' + predicted.getFullYear();
    var leftDays =  ( predicted.getTime() - now.getTime() ) / (24*3600*1000); 
    var currentWeeks = (now.getTime() - initial.getTime()) / (7*24*3600*1000)
    document.getElementById('results').innerHTML = '<p>Your estimated due date is ' + formated + '</p><p>Days left to your date: '+ parseInt(leftDays) +'</p><p>Weeks of pregnancy: '+ Math.round(currentWeeks) +'</p>';
  }
</script>