This is where you start. This is a recursive function that I wrote some time ago (part of Project Euler 's solution to Problem 17 ), which converts numbers to letters ... It can handle some pretty large numbers;)
All you have to do is add the components of dollars and cents and change as needed. So basically, you will need to call the function once for the dollar amount and once for the cents component. I do not think there is a built-in PHP function for this. You will need to use a library function (e.g. Pear).
(You can see the function in action) :
<?php function translateToWords($number) { /***** * A recursive function to turn digits into words * Numbers must be integers from -999,999,999,999 to 999,999,999,999 inclussive. * * (C) 2010 Peter Ajtai * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * See the GNU General Public License: <http://www.gnu.org/licenses/>. * */ // zero is a special case, it cause problems even with typecasting if we don't deal with it here $max_size = pow(10,18); if (!$number) return "zero"; if (is_int($number) && $number < abs($max_size)) { switch ($number) { // set up some rules for converting digits to words case $number < 0: $prefix = "negative"; $suffix = translateToWords(-1*$number); $string = $prefix . " " . $suffix; break; case 1: $string = "one"; break; case 2: $string = "two"; break; case 3: $string = "three"; break; case 4: $string = "four"; break; case 5: $string = "five"; break; case 6: $string = "six"; break; case 7: $string = "seven"; break; case 8: $string = "eight"; break; case 9: $string = "nine"; break; case 10: $string = "ten"; break; case 11: $string = "eleven"; break; case 12: $string = "twelve"; break; case 13: $string = "thirteen"; break; // fourteen handled later case 15: $string = "fifteen"; break; case $number < 20: $string = translateToWords($number%10); // eighteen only has one "t" if ($number == 18) { $suffix = "een"; } else { $suffix = "teen"; } $string .= $suffix; break; case 20: $string = "twenty"; break; case 30: $string = "thirty"; break; case 40: $string = "forty"; break; case 50: $string = "fifty"; break; case 60: $string = "sixty"; break; case 70: $string = "seventy"; break; case 80: $string = "eighty"; break; case 90: $string = "ninety"; break; case $number < 100: $prefix = translateToWords($number-$number%10); $suffix = translateToWords($number%10); $string = $prefix . "-" . $suffix; break; // handles all number 100 to 999 case $number < pow(10,3): // floor return a float not an integer $prefix = translateToWords(intval(floor($number/pow(10,2)))) . " hundred"; if ($number%pow(10,2)) $suffix = " and " . translateToWords($number%pow(10,2)); $string = $prefix . $suffix; break; case $number < pow(10,6): // floor return a float not an integer $prefix = translateToWords(intval(floor($number/pow(10,3)))) . " thousand"; if ($number%pow(10,3)) $suffix = translateToWords($number%pow(10,3)); $string = $prefix . " " . $suffix; break; case $number < pow(10,9): // floor return a float not an integer $prefix = translateToWords(intval(floor($number/pow(10,6)))) . " million"; if ($number%pow(10,6)) $suffix = translateToWords($number%pow(10,6)); $string = $prefix . " " . $suffix; break; case $number < pow(10,12): // floor return a float not an integer $prefix = translateToWords(intval(floor($number/pow(10,9)))) . " billion"; if ($number%pow(10,9)) $suffix = translateToWords($number%pow(10,9)); $string = $prefix . " " . $suffix; break; case $number < pow(10,15): // floor return a float not an integer $prefix = translateToWords(intval(floor($number/pow(10,12)))) . " trillion"; if ($number%pow(10,12)) $suffix = translateToWords($number%pow(10,12)); $string = $prefix . " " . $suffix; break; // Be careful not to pass default formatted numbers in the quadrillions+ into this function // Default formatting is float and causes errors case $number < pow(10,18): // floor return a float not an integer $prefix = translateToWords(intval(floor($number/pow(10,15)))) . " quadrillion"; if ($number%pow(10,15)) $suffix = translateToWords($number%pow(10,15)); $string = $prefix . " " . $suffix; break; } } else { echo "ERROR with - $number<br/> Number must be an integer between -" . number_format($max_size, 0, ".", ",") . " and " . number_format($max_size, 0, ".", ",") . " exclussive."; } return $string; } ?>