Here is one I've used in the past just change the dates to your end date and edit size of font etc. Hope it's of use
PHP Code:
<script LANGUAGE="JavaScript">
var present;
var future;
var tseconds;
var seconds;
var minutes;
var hours;
var days;
ID=setTimeout("countdown();", 1000);
function countdown()
{
present = new Date();
present = present.getTime() + (60000) + (12 * 60 * 60 * 1000);
future = new Date("December 18, 2012 23:59:00");
tseconds = (future - present) / 1000;
days = tseconds /24/60/60;
days = Math.floor(days);
tseconds = tseconds - (days * 24 * 60 * 60);
hours = tseconds /60/60;
hours = Math.floor(hours);
tseconds = tseconds - (hours * 60 * 60);
minutes = tseconds /60;
minutes = Math.floor(minutes);
tseconds = tseconds - (minutes * 60);
seconds = tseconds;
seconds = Math.floor(seconds);
document.getElementById('days').innerHTML = days;
document.getElementById('hours').innerHTML = hours;
document.getElementById('minutes').innerHTML = minutes;
document.getElementById('seconds').innerHTML = seconds;
ID=setTimeout("countdown();", 1000);
}
</script>
<script LANGUAGE="JavaScript">
today = new Date();
todayEpoch = today.getTime();
target = new Date("18 December, 2012");
targetEpoch = target.getTime();
daysLeft = Math.floor(((targetEpoch - todayEpoch) / (60*60*24)) / 1000);
</script>
<br>
<div style="TEXT-ALIGN: center">
<font size="6"><strong>
<SPAN id="days">0</SPAN> Days.
<SPAN id="hours">0</SPAN> hr.
<SPAN id="minutes">0</SPAN> min,
<SPAN id="seconds">0</SPAN> sec. </font>
</div>