How to Specify the Time Zone as UTC When Using the PHP DateTime Class?

Get Current Date/Time in UTC Using DateTime Class

To get the current time in UTC with the DateTime class, we can simply specify the UTC time zone with an instance of DateTimeZone like so:

$utcDateTime = new DateTime('now', new DateTimeZone('UTC'));

echo $utcDateTime->format('Y-m-d H:i:s'); // output: '2020-12-31 22:28:21'

Convert Existing Date/Time Into UTC Using DateTime Class

To convert the time zone to UTC of an existing DateTime class instance, we can do the following:

$utcDateTime->setTimezone(new DateTimeZone('UTC'));

echo $utcDateTime->format('Y-m-d H:i:s'); // output: '2020-12-31 22:28:21'

If the existing date/time is not already an instance of DateTime class, then we can convert it in the following ways:

$utcDateTime = new DateTime($existingDateTime, new DateTimeZone('UTC'));

echo $utcDateTime->format('Y-m-d H:i:s'); // output: '2020-12-31 22:28:21'

If the existing date/time has a custom format (which the DateTime object cannot automatically convert or recognize), then you can specify the date/time format in the following way and convert it to the DateTime object:

$existingDateTime = date('Y m d H-i-s');

$utcDateTime = DateTime::createFromFormat(
    'Y m d H-i-s',
    $existingDateTime,
    new DateTimeZone('America/New_York')
);

$utcDateTime->setTimezone(new DateTimeZone('UTC'));

echo $utcDateTime->format('Y-m-d H:i:s'); // output: '2020-12-31 22:28:21'