Kahlualator

<html>
<head>
<title>Kahlua Calculator</title>
<script type="text/javascript">
function Kahlualator() {
  var spirit = document.getElementById('amount').value;
  document.getElementById('spirit').innerHTML = spirit;
  var spirit_oz = (spirit*8);
  var spirit_rate = (spirit_oz/4);
  var spirit_mL = roundNumber((spirit_oz*29.5735296),2);
  var proof_now = document.getElementById('strength').value;
  var proof_later = document.getElementById('weakness').value;
  var proof_abv = (proof_later/2);
  document.getElementById('proof_abv').innerHTML = proof_abv;
  var proof_it = roundNumber(spirit*((proof_now/proof_later)-1),2);
  var coffee = (spirit*.25);
  document.getElementById('coffee').innerHTML = coffee;
  // Blend per instructable
  var caramel = roundNumber(((spirit_rate/2)*4),2);
  var sugar = roundNumber(((spirit_rate*1)*4),2);
  var vanilla = roundNumber(((spirit_rate*.0625)*4),2);
  document.getElementById('caramel').innerHTML = caramel;
  document.getElementById('sugar').innerHTML = sugar;
  document.getElementById('vanilla').innerHTML = vanilla;
  var blend = roundNumber((sugar+caramel+vanilla),2);
  document.getElementById('blend').innerHTML = blend;
  var yield = roundNumber((spirit_mL+(blend*29.5735296)),2);
  document.getElementById('yield').innerHTML = yield;
  // Blend per proof calculation
  var caramel2 = roundNumber((1/(1+2))*((proof_it*8)-vanilla),2);
  var sugar2 = roundNumber((2/(1+2))*((proof_it*8)-vanilla),2);
  var vanilla2 = roundNumber(((spirit_rate*.0625)*4),2); // Same as instructable
  document.getElementById('caramel2').innerHTML = caramel2;
  document.getElementById('sugar2').innerHTML = sugar2;
  document.getElementById('vanilla2').innerHTML = vanilla2;
  var blend2 = roundNumber((sugar2+caramel2+vanilla2),2);
  document.getElementById('blend2').innerHTML = blend2;
  var yield2 = roundNumber((spirit_mL+(blend2*29.5735296)),2);
  document.getElementById('yield2').innerHTML = yield2;
}
function roundNumber(num, dec) {
    var result = Math.round(num*Math.pow(10,dec))/Math.pow(10,dec);
    return result;
}
</script>
</head>
  <body style='margin:5px;border:1px dashed #cccccc;padding:5px;'>
    <form>
      <input type='text' id='amount' value='5'/>  Cup(s) of spirit to be infused
      <br/><br/>
      <input type='text' id='strength' value='80'/>  Proof of spirit to be infused
      <br/><br/>
      <!-- Proof: 53 Mexico / 40 - 43 USA / 31.2 per instructable -->
      <input type='text' id='weakness' value='31.2'/>  Proof of final product
      <br/><br/>
      <input type="button" value="Calculate" onclick="Kahlualator()">
      <br/><br/>
      <!-- Instructions -->
      Infuse <span id='spirit'></span>&nbsp;cup(s) of spirit
      with <span id='coffee'></span>&nbsp;cup(s) of coffee.
      <br/><br/>
      Blend per instructable:<br/>
      <span id='caramel'></span>&nbsp;oz Caramel<br/>
      <span id='sugar'></span>&nbsp;oz Sugar*<br/>
      <span id='vanilla'></span>&nbsp;oz Vanilla<br/>
      <span id='blend'></span>&nbsp;oz Total<br/>
      <br/>
      Approximates of final product:<br/>
      ABV 15.6%<br/>
      Yield <span id='yield'></span>&nbsp;mL<br/>
      <br/>
      Blend per proof calculation:<br/>
      <span id='caramel2'></span>&nbsp;oz Caramel<br/>
      <span id='sugar2'></span>&nbsp;oz Sugar*<br/>
      <span id='vanilla2'></span>&nbsp;oz Vanilla<br/>
      <span id='blend2'></span>&nbsp;oz Total Dilution<br/>
      <br/>
      Approximates of final product:<br/>
      ABV <span id='proof_abv'></span>%<br/>
      Yield <span id='yield2'></span>&nbsp;mL<br/>
      <br/>
      * Note: Sugar needs to be reduced 10%
    </form>
  </body>
</html>