[php] Convert UTC dates to local time in PHP

I'm storing the UTC dates into the DB using:

$utc = gmdate("M d Y h:i:s A");

and then I want to convert the saved UTC date to the client's local time.

How can I do that?

Thanks

Here I am sharing the script, convert UTC timestamp to Indian timestamp:-

    // create a $utc object with the UTC timezone
    $IST = new DateTime('2016-12-12 12:12:12', new DateTimeZone('UTC'));

    // change the timezone of the object without changing it's time
    $IST->setTimezone(new DateTimeZone('Asia/Kolkata'));

    // format the datetime
   echo $IST->format('Y-m-d H:i:s T');

$UTC_Time   = "2018-07-06 06:06:16";
echo "UTC Time ".$UTC_Time;
$Indian_Time = TimeConverion($UTC_Time);
echo "<br> Indian_Time ".$Indian_Time;

function TimeConverion($UTC_Time) {
  date_default_timezone_set('Europe/London');
  $sTime = date("Y-m-d h:i:sa");
  $ts3 = strtotime(date("G:i:s"))-strtotime($sTime); 
  $utc = explode(" ",$UTC_Time);
  $time = strtotime($utc[1]);
  date_default_timezone_set("Asia/Calcutta");
  $time += $ts3;  // Add the difference
  return $utc[0]." ".date("H:i:s", $time);
}

Given a local timezone, such as 'America/Denver', you can use DateTime class to convert UTC timestamp to the local date:

$timestamp = *********;
$date = new DateTime("@" . $timestamp);
$date->setTimezone(new DateTimeZone('America/Denver'));
echo $date->format('Y-m-d H:i:s');

Answer

Convert the UTC datetime to America/Denver

// create a $dt object with the UTC timezone
$dt = new DateTime('2016-12-12 12:12:12', new DateTimeZone('UTC'));

// change the timezone of the object without changing it's time
$dt->setTimezone(new DateTimeZone('America/Denver'));

// format the datetime
$dt->format('Y-m-d H:i:s T');

Notes

time() returns the unix timestamp, which is a number, it has no timezone.

date('Y-m-d H:i:s T') returns the date in the current locale timezone.

gmdate('Y-m-d H:i:s T') returns the date in UTC

date_default_timezone_set() changes the current locale timezone

to change a time in a timezone

// create a $dt object with the America/Denver timezone
$dt = new DateTime('2016-12-12 12:12:12', new DateTimeZone('America/Denver'));

// change the timezone of the object without changing it's time
$dt->setTimezone(new DateTimeZone('UTC'));

// format the datetime
$dt->format('Y-m-d H:i:s T');

here you can see all the available timezones

https://en.wikipedia.org/wiki/List_of_tz_database_time_zones

here are all the formatting options

http://php.net/manual/en/function.date.php

Update PHP timezone DB (in linux)

sudo pecl install timezonedb

PHP's strtotime function will interpret timezone codes, like UTC. If you get the date from the database/client without the timezone code, but know it's UTC, then you can append it.

Assuming you get the date with timestamp code (like "Fri Mar 23 2012 22:23:03 GMT-0700 (PDT)", which is what Javascript code ""+(new Date()) gives):

$time = strtotime($dateWithTimeZone);
$dateInLocal = date("Y-m-d H:i:s", $time);

Or if you don't, which is likely from MySQL, then:

$time = strtotime($dateInUTC.' UTC');
$dateInLocal = date("Y-m-d H:i:s", $time);

Here is a straight way to convert the UTC time of the questioner to local time. This is for a stored time in a database etc., i.e. any time. You just have to find the time difference between UTC time and the local time you are interested in and then ajust the stored UTC time adding to it the difference.

$df = "G:i:s";  // Use a simple time format to find the difference
$ts1 = strtotime(date($df));   // Timestamp of current local time
$ts2 = strtotime(gmdate($df)); // Timestamp of current UTC time
$ts3 = $ts1-$ts2;              // Their difference

You can then add this difference to the stored UTC time. (In my place, Athens, the difference is exactly 5:00:00)

Example:

$time = time() // Or any other timestamp
$time += $ts3  // Add the difference
$dateInLocal = date("Y-m-d H:i:s", $time);

I store date in the DB in UTC format but then I show them to the final user in their local timezone

// retrieve
$d = (new \DateTime($val . ' UTC'))->format('U');
return date("Y-m-d H:i:s", $d);

Date arithmetic is not needed if you just want to display the same timestamp in different timezones:

$format = "M d, Y h:ia";
$timestamp = gmdate($format);

date_default_timezone_set("UTC");
$utc_datetime = date($format, $timestamp);

date_default_timezone_set("America/Guayaquil");
$local_datetime = date($format, $timestamp);

First, get the date in UTC -- you've already done that so this step would really just be a database call:

$timezone = "UTC";
date_default_timezone_set($timezone);

$utc = gmdate("M d Y h:i:s A");
print "UTC: " . date('r', strtotime($utc)) . "\n";

Next, set your local time zone in PHP:

$timezone = "America/Guayaquil";
date_default_timezone_set($timezone);

And now get the offset in seconds:

$offset = date('Z', strtotime($utc));
print "offset: $offset \n";

Finally, add the offset to the integer timestamp of your original datetime:

print "LOCAL: " . date('r', strtotime($utc) + $offset) . "\n";