<?php
/*
+----------------------------------------------------
| Calcular data no formato YYYY-mm-dd HH:ii:ss 
| Utiliza assim: calc_date("2008-01-01 12:30:00", "2008-01-09 18:30:00");
+----------------------------------------------------
*/ 
function calc_date($dia1, $dia2) {

$x = strtotime($dia1);
$y = strtotime($dia2);

$dias = ($y - $x)  / 86400;

$diff = $y - $x;

if($diff % 86400 <= 0)
    {$days = $diff / 86400;}

 if($diff % 86400 > 0)
   {   $rest = ($diff % 86400);
       $days = ($diff - $rest) / 86400;
       if( $rest % 3600 > 0 )
       {   $rest1 = ($rest % 3600);
           $hours = ($rest - $rest1) / 3600;
           if( $rest1 % 60 > 0 )
           {   $rest2 = ($rest1 % 60);
               $minutes = ($rest1 - $rest2) / 60;
               $seconds = $rest2;
           }else
               $minutes = $rest1 / 60;
       }else
           $hours = $rest / 3600;}

if($days > "1"){ $s1 = "s";};
if($hours > "1"){ $s2 = "s";};
if($minutes > "1"){ $s3 = "s";};
if($seconds > "1"){ $s4 = "s";};

if($days != ""){echo $days." Dia".$s1." ";}
if($hours != ""){echo $hours." Hora".$s2." ";}
if($minutes != ""){echo $minutes." minuto".$s3." ";}
if($seconds != ""){echo $seconds." segundo".$s4." ";}
}
?>