Elegant way to get the count of months between two dates? - php

Question

Let's assume I have two dates in variables, like
$date1 = "2009-09-01";
$date2 = "2010-05-01";
I need to get the count of months between $date2 and $date1($date2 >= $date1). I.e. i need to get 8.
Is there a way to get it by using date function, or I have to explode my strings and do required calculations?
Thanks.

Answer 1

For PHP >= 5.3
$d1 = new DateTime("2009-09-01");
$d2 = new DateTime("2010-05-01");
var_dump($d1->diff($d2)->m); // int(4)
var_dump($d1->diff($d2)->m + ($d1->diff($d2)->y*12)); // int(8)
DateTime::diff returns a DateInterval object
If you don't run with PHP 5.3 or higher, I guess you'll have to use unix timestamps :
$d1 = "2009-09-01";
$d2 = "2010-05-01";
echo (int)abs((strtotime($d1) - strtotime($d2))/(60*60*24*30)); // 8
But it's not very precise (there isn't always 30 days per month).
Last thing : if those dates come from your database, then use your DBMS to do this job, not PHP.
Edit: This code should be more precise if you can't use DateTime::diff or your RDBMS :
$d1 = strtotime("2009-09-01");
$d2 = strtotime("2010-05-01");
$min_date = min($d1, $d2);
$max_date = max($d1, $d2);
$i = 0;
while (($min_date = strtotime("+1 MONTH", $min_date)) <= $max_date) {
$i++;
}
echo $i; // 8

Answer 2

Or, if you want the procedural style:
$date1 = new DateTime("2009-09-01");
$date2 = new DateTime("2010-05-01");
$interval = date_diff($date1, $date2);
echo $interval->m + ($interval->y * 12) . ' months';
UPDATE: Added the bit of code to account for the years.

Answer 3

Or a simple calculation would give :
$numberOfMonths = abs((date('Y', $endDate) - date('Y', $startDate))*12 + (date('m', $endDate) - date('m', $startDate)))+1;
Accurate and works in all cases.

Answer 4

This is another way to get the number of months between two dates:
// Set dates
$dateIni = '2014-07-01';
$dateFin = '2016-07-01';
// Get year and month of initial date (From)
$yearIni = date("Y", strtotime($dateIni));
$monthIni = date("m", strtotime($dateIni));
// Get year an month of finish date (To)
$yearFin = date("Y", strtotime($dateFin));
$monthFin = date("m", strtotime($dateFin));
// Checking if both dates are some year
if ($yearIni == $yearFin) {
$numberOfMonths = ($monthFin-$monthIni) + 1;
} else {
$numberOfMonths = ((($yearFin - $yearIni) * 12) - $monthIni) + 1 + $monthFin;
}

Answer 5

I use this:
$d1 = new DateTime("2009-09-01");
$d2 = new DateTime("2010-09-01");
$months = 0;
$d1->add(new \DateInterval('P1M'));
while ($d1 <= $d2){
$months ++;
$d1->add(new \DateInterval('P1M'));
}
print_r($months);

Answer 6

Using DateTime, this will give you a more accurate solution for any amount of months:
$d1 = new DateTime("2011-05-14");
$d2 = new DateTime();
$d3 = $d1->diff($d2);
$d4 = ($d3->y*12)+$d3->m;
echo $d4;
You would still need to handle the leftover days $d3->d if your real world problem is not as simple and cut and dry as the original question where both dates are on the first of the month.

Answer 7

This is a simple method I wrote in my class to count the number of months involved into two given dates :
public function nb_mois($date1, $date2)
{
$begin = new DateTime( $date1 );
$end = new DateTime( $date2 );
$end = $end->modify( '+1 month' );
$interval = DateInterval::createFromDateString('1 month');
$period = new DatePeriod($begin, $interval, $end);
$counter = 0;
foreach($period as $dt) {
$counter++;
}
return $counter;
}

Answer 8

In case the dates are part of a resultset from a mySQL query, it is much easier to use the TIMESTAMPDIFF function for your date calculations and you can specify return units eg. Select TIMESTAMPDIFF(MONTH, start_date, end_date)months_diff from table_name

Answer 9

strtotime is not very precise, it makes an approximate count, it does not take into account the actual days of the month.
it's better to bring the dates to a day that is always present in every month.
$date1 = "2009-09-01";
$date2 = "2010-05-01";
$d1 = mktime(0, 0, 1, date('m', strtotime($date1)), 1, date('Y', strtotime($date1)));
$d2 = mktime(0, 0, 1, date('m', strtotime($date2)), 1, date('Y', strtotime($date2)));
$total_month = 0;
while (($d1 = strtotime("+1 MONTH", $d1)) <= $d2) {
$total_month++;
}
echo $total_month;

Answer 10

I have used this and works in all conditions
$fiscal_year = mysql_fetch_row(mysql_query("SELECT begin,end,closed FROM fiscal_year WHERE id = '2'"));
$date1 = $fiscal_year['begin'];
$date2 = $fiscal_year['end'];
$ts1 = strtotime($date1);
$ts2 = strtotime($date2);
$te=date('m',$ts2-$ts1);
echo $te;