Calculate the amount of time between two dates/timestamps in PHP. Return the result as a nicely formatted string or an array of data.

relative_time.php

<?php

/**
 * Get the relative time between two timestamps.
 * 
 * @access public
 * @param integer|string $time The date or timestamp that represents the time we're comparing to.
 * @param integer|string $comparison_time [optional] The date or timestamp we want comparisons to be relative to. Defaults to the current timestamp.
 * @param boolean $return_array [optional] Whether to return the relative time as an array of components rather than a string. Default value is FALSE.
 * @return string Returns the amount of time between the two timestamps as a string or an array if $return_array is TRUE.
 */
function relative_time($time, $comparison_time = null, $return_array = false) {
	
	// static data
	static $time_units = array(
		'year' => 31536000,
		'month' => 2678400,
		'week' => 604800,
		'day' => 86400,
		'hour' => 3600,
		'minute' => 60,
		'second' => 1
	);
	
	// sanitize arguments
	$time = (is_string($time) ? strtotime($time) : (integer) $time);
	$comparison_time = ($comparison_time === null ? time() : (is_string($comparison_time) ? strtotime($comparison_time) : (integer) $comparison_time));
	$return_array = (boolean) $return_array;
	
	// get time difference
	$time_difference =  $time - $comparison_time;
	$time_difference_positive = abs($time_difference);
	
	// get the prefix/suffix
	$time_prefix = '';
	$time_suffix = '';
	if ($time_difference < 0) {
		$time_suffix = 'ago';
	}
	else if ($time_difference > 0) {
		$time_prefix = 'in';
	}
	
	// get the unit
	$time_unit = 'second';
	$unit_time_difference = $time_difference_positive;
	foreach ($time_units as $unit => $unit_seconds) {
		if ($time_difference_positive >= $unit_seconds) {
			$unit_time_difference = round($time_difference_positive / $unit_seconds);
			$time_unit = $unit;
			break;
		}
	}
	
	// pluralise unit
	if ($unit_time_difference > 1) {
		$time_unit .= 's';
	}
	
	// return
	if ($return_array) {
		
		// return relative time as an array
		$relative_time = array(
			'offset' => $unit_time_difference,
			'offset_seconds' => $time_difference_positive,
			'unit' => $time_unit,
			'unit_plural' => ($unit_time_difference > 1),
			'prefix' => $time_prefix,
			'suffix' => $time_suffix
		);
		return $relative_time;
		
	}
	else {
		
		// return relative time as a string
		$relative_time = ($time_prefix ? $time_prefix . ' ' : '') . $unit_time_difference . ' ' . $time_unit . ($time_suffix ? ' ' . $time_suffix : '');
		return ($time_difference == 0 ? 'just now' : $relative_time);
		
	}
	
}

?>