Convert Excel dates into PHP timestamps

Having trouble getting your PHP script to build dates from Excel using mktime() ?  Me too. Everything’s one day off?  I know it.  Here’s what I found.

The proper way to convert Excel dates into PHP-friendly timestamps using mktime():

PHP Code:

---

// The date 6/30/2009 is stored as 39994 in Excel
$days = 39994;

// But you must subtract 1 to get the correct timestamp
$ts = mktime(0,0,0,1,[B]$days-1[/B],1900);

// So, this would then match Excel’s representation:
echo date(“m/d/Y”,$ts); 


---

Excel uses “number of days since Jan. 1, 1900″ to store its dates.  It also treats 1900 as a leap year when it wasn’t, thus there is an extra day which must be accounted for in PHP (and the rest of the world).  Subtracting 1 from Excel’s number will fix this problem.

Excel stores dates internally as number of days since January 1, 1900.
For example: "June 9th, 2011 10:30 AM" would be stored as "40703.4375".
40703 is the number of full days since 01/01/1900 and 0.4375 represents the time (10.5/24 = 0.4375).

When you process dates read from an Excel spreadsheet (e.g. using PHPExcel) you often want to convert them into a UNIX timestamp i.e. a number of seconds elapsed since midnight of January 1, 1970 UTC.

Here is a PHP code to do that:

PHP Code:

---

// Numbers of days between January 1, 1900 and 1970 (including 19 leap years)
define("MIN_DATES_DIFF", 25569);
  
// Numbers of second in a day:
define("SEC_IN_DAY", 86400);   
 
function excel2timestamp($excelDate)
{
   if ($excelDate <= MIN_DATES_DIFF)
      return 0;
 
   return  ($excelDate - MIN_DATES_DIFF) * SEC_IN_DAY;
} 


---

Although the code above is written in PHP the function should be very similar in any other language e.g. C# or java. If the provided date is earlier than 1/1/1970 then the minimal timestamp value will be returned.

Alternative solution:

If you provide the Excel spreadsheet that you later on read from in your app you could add a hidden cell that would calculate the timestamp for you, within the spreadsheet.
Assuming that B2 is the cell that stores your date the formula for calculating timestamp would be:

Code:

---

=(B2-DATE(1970,1,1))*86400

---

Now you only need to read the calculated value from the hidden cell.

Source: blogspot.com

40703 is the quantity of entire days since 01/01/1900 and 0.4375 speaks to the time (10.5/24 = 0.4375). When you process dates read from an Excel spreadsheet (for example utilizing PHPExcel) you regularly need to change over them into a UNIX timestamp for example various seconds passed since midnight of January 1, 1970 UTC.

Thank You!

Convert Unix dates for export to Excel with PHP or MySQL Unix timestamps are in UTC (GMT), so the first thing we need to do is convert to

Convert Excel dates into PHP timestamps. Experiencing difficulty getting your PHP content to fabricate dates from Excel utilizing mktime() ? Me as well. Everything's..