PHP Date Format: Every date() Format Character

A PHP date format is a string where letters stand for parts of the date: date('Y-m-d H:i:s') prints something like 2026-03-14 09:05:07. Y is the 4-digit year, m the month, d the day, H the hour (24-hour clock), i the minutes and s the seconds; any character that is not a format letter, such as -, / or :, is printed as it is. The same format strings work in date() and in DateTimeImmutable::format().

Change $format and press Run. The date is fixed to Saturday, March 14, 2026 at 09:05:07, so you can see exactly what each letter does:

<?php
$date = new DateTimeImmutable('2026-03-14 09:05:07');

$format = 'D, d M Y H:i';   // edit me

echo $date->format($format), "\n";
echo $date->format('Y-m-d'), "\n";
echo $date->format('d/m/Y'), "\n";
echo $date->format('l, F jS, Y'), "\n";
echo $date->format('g:i A'), "\n";

Output:

Sat, 14 Mar 2026 09:05
2026-03-14
14/03/2026
Saturday, March 14th, 2026
9:05 AM

date($format) formats the current moment and date($format, $timestamp) a timestamp; $date->format($format) formats a date object. Everything else about dates, from strtotime() to timezones, is on the PHP date() page.

Date format characters

Every example below is the result for 2026-03-14 09:05:07.123456 UTC.

Day

Week and month

Year

Time

Timezone

Full date and time

The same table, live: this block prints every character for a date you choose. Put in your birthday, a date in the afternoon, or one at the end of a leap year:

<?php
$date = new DateTimeImmutable('2026-03-14 09:05:07.123456');   // try '2028-12-31 18:45'

foreach (str_split('djDlNwSzWFMmntYyLoXxHGhgisaAvuBeTPpOZIcrU') as $char) {
    echo $char, '  ', $date->format($char), "\n";
}

Print letters and words inside a format

Any letter in a format string is read as a format character, so 'Today is l' does not print "Today is": T, o, d, a, y, i and s are all format characters. Put a backslash before each letter you want printed as it is. In a double-quoted string, \t is already a tab character, so use single quotes for formats with backslashes:

<?php
$date = new DateTimeImmutable('2026-03-14 09:05:07');

echo $date->format('Today is l'), "\n";            // letters read as format characters
echo $date->format('\T\o\d\a\y \i\s l'), "\n";     // escaped
echo $date->format('l \t\h\e jS \o\f F'), "\n";
echo $date->format('Y-m-d\TH:i:s'), "\n";          // a literal T between date and time

echo $date->format("l \the jS"), "\n";             // double quotes: \t is a tab, h and e are format letters

Output:

UTC202614am26 0507 Saturday
Today is Saturday
Saturday the 14th of March
2026-03-14T09:05:07
Saturday 	09UTC 14th

Common date formats

Most code needs only a handful of formats. This block prints them as an HTML table, so it shows up on the Page tab:

<?php
$date = new DateTimeImmutable('2026-03-14 15:45:00');

$formats = [
    'Y-m-d'       => 'ISO date, sorts correctly as text',
    'Y-m-d H:i:s' => 'MySQL DATETIME',
    'm/d/Y'       => 'United States',
    'd/m/Y'       => 'UK, Europe, most of the world',
    'd.m.Y'       => 'Germany, Russia',
    'F j, Y'      => 'Long US style',
    'j F Y'       => 'Long UK style',
    'D, M j'      => 'Short, for lists',
    'g:i a'       => '12-hour clock',
    'H:i'         => '24-hour clock',
];
?>
<table border="1" cellpadding="6" style="border-collapse: collapse">
    <tr><th>Format</th><th>Result</th><th>Used for</th></tr>
<?php foreach ($formats as $format => $use): ?>
    <tr>
        <td><code><?= $format ?></code></td>
        <td><?= $date->format($format) ?></td>
        <td><?= $use ?></td>
    </tr>
<?php endforeach; ?>
</table>

Store and compare dates as Y-m-d or Y-m-d H:i:s: strings in that order sort the same way the dates do, which d/m/Y strings do not.

ISO 8601, DATE_ATOM and other standard formats

PHP has constants for the formats that APIs, feeds and cookies expect. DATE_ATOM (also DateTimeInterface::ATOM) is ISO 8601 and RFC 3339, the format JSON APIs use:

<?php
$date = new DateTimeImmutable('2026-03-14 09:05:07');

echo $date->format(DATE_ATOM), "\n";               // ISO 8601
echo $date->format('c'), "\n";                     // the same, as a character
echo $date->format(DATE_RFC3339_EXTENDED), "\n";   // with milliseconds
echo $date->format(DATE_RFC2822), "\n";            // email headers
echo $date->format(DATE_RSS), "\n";                // RSS feeds
echo $date->format(DATE_COOKIE), "\n";             // cookies

echo DATE_ATOM, "\n";                              // the format string behind it

Output:

2026-03-14T09:05:07+00:00
2026-03-14T09:05:07+00:00
2026-03-14T09:05:07.000+00:00
Sat, 14 Mar 2026 09:05:07 +0000
Sat, 14 Mar 2026 09:05:07 +0000
Saturday, 14-Mar-2026 09:05:07 UTC
Y-m-d\TH:i:sP

There is also a DATE_ISO8601 constant, but its offset has no colon (+0000), which ISO 8601 does not allow in that form; use DATE_ATOM.

Japanese date format (Y年m月d日)

Characters that are not format letters are printed as they are, and that includes kanji, so 'Y年n月j日' works as written. n and j drop the leading zero (3月14日), m and d keep it (03月14日). The day name is the one part date() cannot translate, because it only knows English names; map the w number to your own list instead:

<?php
$date = new DateTimeImmutable('2026-03-14 09:05:07');
$weekdays = ['日', '月', '火', '水', '木', '金', '土'];   // w: 0 = Sunday

echo $date->format('Y年n月j日'), "\n";
echo $date->format('Y年m月d日 H時i分'), "\n";
echo $date->format('Y年n月j日'), '(', $weekdays[$date->format('w')], ")\n";
echo $date->format('Y/m/d'), "\n";

Output:

2026年3月14日
2026年03月14日 09時05分
2026年3月14日(土)
2026/03/14

For full localization, including month names in other languages and the Japanese era (令和), the intl extension's IntlDateFormatter formats with locale patterns. It uses ICU pattern letters (yyyy, MM, EEEE), not the PHP characters on this page:

<?php
$formatter = new IntlDateFormatter('ja_JP', IntlDateFormatter::FULL, IntlDateFormatter::NONE, 'Asia/Tokyo');
echo $formatter->format(new DateTimeImmutable('2026-03-14')); // 2026年3月14日土曜日

$era = new IntlDateFormatter('ja_JP@calendar=japanese', IntlDateFormatter::LONG, IntlDateFormatter::NONE, 'Asia/Tokyo', IntlDateFormatter::TRADITIONAL);
echo $era->format(new DateTimeImmutable('2026-03-14'));       // 令和8年3月14日

Convert a date from one format to another

To turn 14/03/2026 into 2026-03-14, parse the string with the format it is written in, using DateTimeImmutable::createFromFormat(), then format it again. It uses the same characters as the table. Start the format with !, or fields you did not give (the time, here) are filled in from the current moment:

<?php
$input = '14/03/2026';

$date = DateTimeImmutable::createFromFormat('!d/m/Y', $input);
if ($date === false) {
    exit("Not a d/m/Y date\n");
}
echo $date->format('Y-m-d H:i:s'), "\n";
echo $date->format('F j, Y'), "\n";

// The string must match the format, or you get false
var_dump(DateTimeImmutable::createFromFormat('!d/m/Y', '2026-03-14'));

// A date that does not exist overflows, and getLastErrors() says so
$feb31 = DateTimeImmutable::createFromFormat('!d/m/Y', '31/02/2026');
echo $feb31->format('Y-m-d'), "\n";
print_r(DateTimeImmutable::getLastErrors()['warnings']);

Output:

2026-03-14 00:00:00
March 14, 2026
bool(false)
2026-03-03
Array
(
    [10] => The parsed date was invalid
)

For dates typed by users, treat any warning from getLastErrors() as an invalid date, the same way you treat false.

Common mistakes with date formats

Three bugs show up again and again: m where i was meant, Y versus y, and letting strtotime() guess the order of day and month. strtotime() reads slashes as American month/day order and dashes or dots as day-month order, so the same digits give two different dates:

<?php
$date = new DateTimeImmutable('2026-03-14 09:05:07');

echo $date->format('H:m:s'), "\n";   // wrong: m is the month
echo $date->format('H:i:s'), "\n";   // right: i is the minutes
echo $date->format('d/m/y'), "\n";   // y: 2-digit year

echo date('Y-m-d', strtotime('03/04/2026')), "\n";   // m/d/Y: March 4
echo date('Y-m-d', strtotime('03-04-2026')), "\n";   // d-m-Y: April 3
var_dump(strtotime('14/03/2026'));                   // no month 14: false

Output:

09:03:07
09:05:07
14/03/26
2026-03-04
2026-04-03
bool(false)

When you know the format of the input, say it with createFromFormat() instead of letting strtotime() guess.