HFS/HFS+ timestamp

HFS/HFS+ timestamp is a timestamp format associated with the HFS and HFS+ filesystems, and classic Macintosh computers. It appears in some file formats, for example ZIP extensible data field 0x334d (Info-ZIP Macintosh).

It has been called by many other names, including Apple timestamp, Mac OS timestamp, and HFS time; though confusion may exist due to conflation of timestamp formats with timestamp epochs.

It is the number of (non-leap) seconds since the beginning of 1904. This date is the standard epoch for classic Macintosh computers.

It is usually stored as a 32-bit unsigned integer, in which case it can represent dates from about 1904-01-01 to 2040-02-06.

It could be in universal time (UTC), or in local time (perhaps with a separate field for the timezone offset). Reportedly, it is in local time for HFS, and UTC for HFS+.

In UTC, it differs from Unix time by 2082844800.

Links

 * EpochConverter: Mac HFS+ Timestamp Converter
 * Epoch (reference date) - Search for "January 1, 1904", for examples of things that might use this format or a similar format