diff --git a/Understanding-the-Photos-database.md b/Understanding-the-Photos-database.md
index 46a4d13..8d412c7 100644
--- a/Understanding-the-Photos-database.md
+++ b/Understanding-the-Photos-database.md
@@ -33,6 +33,12 @@ The version is a 4-digit integer, the first digit of which signifies which versi
 
 Most of what is described in the following comes from reverse engineering what Photos is doing or looking at the code of [others](https://github.com/RhetTbull/osxphotos/wiki/Related-projects) who have done related work.  I had to make many, many assumptions and some of them are surely wrong.  If you discover any errors or have additional information to add I welcome edits to the wiki or opening an [issue](https://github.com/RhetTbull/osxphotos/issues)!
 
+## dates/times in the database
+Dates & times in the database are stored as a MacOS time value which is the number of seconds since 2001-01-01 00:00:00.  To work with these in python, you'll need add the number of seconds since the Unix time epoch of 1970-01-01 00:00:00.  I do this by computing a time delta thusly:
+
+```python
+td = (datetime(2001, 1, 1, 0, 0) - datetime(1970, 1, 1, 0, 0)).total_seconds()```
+
 Additional details about the Photos 5 database structure are [here](https://github.com/RhetTbull/osxphotos/wiki/Photos-version-5-database).
 
 Additional details about the Photos 4 database structure are [here](https://github.com/RhetTbull/osxphotos/wiki/Photos-version-4-database).