PHP Calendar Functions
Last updated: April 6, 2026
Minimum PHP Version: PHP 4.3+
Overview
The calendar extension contains functions that simplify converting between different calendar formats. It is based on the Julian Day Count, which is a count of days starting from January 1st, 4713 B.C.
When to Use
- Converting between different calendar systems
- Calculating Easter dates
- Working with historical calendars (Gregorian, Julian, Hebrew, French Republican)
- Date calculations and conversions
- International applications requiring multiple calendar formats
Basic Example
<?php
// Convert Gregorian date to Julian Day Count
$jd = gregoriantojd(4, 6, 2026);
echo $jd; // Output: Julian Day Count
// Convert back to Gregorian
$date = jdtogregorian($jd);
echo $date; // Output: 4/6/2026
?>
Advanced Example
<?php
// Calculate Easter date for a year
$easter = easter_date(2026);
echo date("M d, Y", $easter); // Output: Apr 05, 2026
// Get days after March 21
$days = easter_days(2026);
echo "Easter is $days days after March 21"; // Output: Easter is 15 days after March 21
// Get info about calendars
$info = cal_info();
print_r(array_keys($info)); // Shows available calendars
?>
Related Topics
PHP Version Support
Introduced: PHP 4.3
Minimum Required: PHP 4.3+
Extension: Requires calendar extension
See Also
The calendar extension contains functions that simplifies converting between different calendar formats.
It is based on the Julian Day Count, which is a count of days starting from January 1st, 4713 B.C.
Note: To convert between calendar formats, you must first convert to Julian Day Count, then to the calendar of your choice.
Note: The Julian Day Count is not the same as the Julian Calendar!
PHP Calendar Functions
| Function | Description |
|---|---|
| cal_days_in_month() | Returns the number of days in a month for a specified year and calendar |
| cal_from_jd() | Converts a Julian Day Count into a date of a specified calendar |
| cal_info() | Returns information about a specified calendar |
| cal_to_jd() | Converts a date in a specified calendar to Julian Day Count |
| easter_date() | Returns the Unix timestamp for midnight on Easter of a specified year |
| easter_days() | Returns the number of days after March 21, that the Easter Day is in a specified year |
| frenchtojd() | Converts a French Republican date to a Julian Day Count |
| gregoriantojd() | Converts a Gregorian date to a Julian Day Count |
| jddayofweek() | Returns the day of the week |
| jdmonthname() | Returns a month name |
| jdtofrench() | Converts a Julian Day Count to a French Republican date |
| jdtogregorian() | Converts a Julian Day Count to a Gregorian date |
| jdtojewish() | Converts a Julian Day Count to a Jewish date |
| jdtojulian() | Converts a Julian Day Count to a Julian date |
| jdtounix() | Converts Julian Day Count to Unix timestamp |
| jewishtojd() | Converts a Jewish date to a Julian Day Count |
| juliantojd() | Converts a Julian date to a Julian Day Count |
| unixtojd() | Converts Unix timestamp to Julian Day Count |
PHP Predefined Calendar Constants
| Constant | Type | PHP Version |
|---|---|---|
| CAL_GREGORIAN | Integer | PHP 4 |
| CAL_JULIAN | Integer | PHP 4 |
| CAL_JEWISH | Integer | PHP 4 |
| CAL_FRENCH | Integer | PHP 4 |
| CAL_NUM_CALS | Integer | PHP 4 |
| CAL_DOW_DAYNO | Integer | PHP 4 |
| CAL_DOW_SHORT | Integer | PHP 4 |
| CAL_DOW_LONG | Integer | PHP 4 |
| CAL_MONTH_GREGORIAN_SHORT | Integer | PHP 4 |
| CAL_MONTH_GREGORIAN_LONG | Integer | PHP 4 |
| CAL_MONTH_JULIAN_SHORT | Integer | PHP 4 |
| CAL_MONTH_JULIAN_LONG | Integer | PHP 4 |
| CAL_MONTH_JEWISH | Integer | PHP 4 |
| CAL_MONTH_FRENCH | Integer | PHP 4 |
| CAL_EASTER_DEFAULT | Integer | PHP 4.3 |
| CAL_EASTER_ROMAN | Integer | PHP 4.3 |
| CAL_EASTER_ALWAYS_GREGORIAN | Integer | PHP 4.3 |
| CAL_EASTER_ALWAYS_JULIAN | Integer | PHP 4.3 |
| CAL_JEWISH_ADD_ALAFIM_GERESH | Integer | PHP 5.0 |
| CAL_JEWISH_ADD_ALAFIM | Integer | PHP 5.0 |
| CAL_JEWISH_ADD_GERESHAYIM | Integer | PHP 5.0 |