<form action="converter.php" method="post"> <fieldset><legend>Select Your Input Type and Value</legend> <input type="number" name="inputNumber" step="any" value="" /> <select name="inputFormat"> <optgroup name="Choose"> <option value="meter" id="meter">Meter</option> <option value="cm" id="cm">Cm</option> <option value="foot" id="fot">Fot</option> <option value="inches" id="tum">Tum</option> </optgroup> </select> </fieldset> <fieldset><legend>Select your Output Type</legend> <select name="outputFormat"> <optgroup name="Choose"> <option value="meter" id="meter">Meter</option> <option value="cm" id="cm">Cm</option> <option value="foot" id="fot">Fot</option> <option value="inches" id="tum">Tum</option> </optgroup> </select> </fieldset> <input type="submit" name="submitForm" value="Convert!" /> </form> <?php $outputNumber=0; $inputNumber = (float)$_POST['inputNumber']; $inputFormat = $_POST['inputFormat']; $outputFormat = $_POST['outputFormat']; switch($inputFormat){ case "meter": switch ($outputFormat){ case "meter": $outputNumber = $inputNumber;break; //METER TO METER case "cm": $outputNumber = $inputNumber*100;break; //METER TO CM case "foot": $outputNumber = $inputNumber*3.2808399;break; //METER TO FT case "inches": $outputNumber = $inputNumber*39.3700787;break;//METER TO INCHES } break; case "cm": //ADD CONVERSION SWITCH IN HERE break; case "foot": //ADD CONVERSION SWITCH IN HERE break; case "inches": //ADD CONVERSION SWITCH IN HERE break; } echo $outputNumber; ?>