Systemd, BIOS & Filesystem Timestamp Converter

Q: What is the systemd journal timestamp format?

**Microseconds since epoch** (e.g. `1786624200000000`), with µs resolution — the `_SOURCE_REALTIME_TIMESTAMP` field.

Q: What is the DOS FAT timestamp format?

A 16-bit date + 16-bit time with **2-second granularity** (bits: 7 year, 4 month, 5 day; 5 hour, 6 min, 5 sec/2).

Q: What is the Mac HFS timestamp?

Seconds since **1904-01-01 00:00:00** (the Mac epoch), stored as unsigned 32-bit — it wraps in 2040.

Q: What is the POSIX touch format?

**`[[CC]YY]MMDDhhmm[.ss]`** — e.g. `2608131430.00` for 2026-08-13 14:30. Also accepts `@epoch` seconds.

OS-level timestamps come in many dialects: systemd journal (µs since epoch), BIOS RTC (packed BCD), DOS FAT (2-second granularity), Mac HFS (seconds since 1904), POSIX touch (`yyyymmddhhmm.ss`), and Git commit (`Tue Aug 13 14:30:00 2026 +0000`).

This converter renders your date-time in each system format for forensic analysis, filesystem development and Linux scripting.

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Enter a date-time above to see the conversion results.

Systemd, BIOS & Filesystem Timestamp Converter Quick Reference

Format	Pattern / Description	Example 1	Example 2
Systemd Journal	Microseconds	1786631400000000	1767225600000000
BIOS Time (BCD)	CMOS Hex	0x1430	0x0000
RTC Packed BCD	Hardware Clock	0x260813143000	0x260101000000
DOS / FAT Date	Hex encoded 16-bit	DATE=0x5D0D TIME=0xB3C0	DATE=0x5C21 TIME=0x4000
DOS FAT Date (Hex)	Hex Encoded	DATE=0x5D0D TIME=0xB3C0	DATE=0x5C21 TIME=0x4000
Mac HFS+ / CFAbsoluteTime	Seconds since 2001	3869476200	3850070400
POSIX touch	YYYYMMDDhhmm.ss	202608131430.00	202601010000.00
Git Commit Date	git log format	Thu Aug 13 14:30:00 2026 +0000	Thu Jan 01 00:00:00 2026 +0000
Ansible date_time	yyyy-MM-dd_HH-mm-ss	2026-08-13_14-30-00	2026-01-01_00-00-00

* Examples are rendered in UTC for the fixed sample instants above.

When to Use Systemd, BIOS & Filesystem Timestamp

Forensic timestamp analysis

Decode FAT/HFS file times from disk images when correlating file activity with system logs.

Linux scripting

Generate `touch -t` arguments and verify `stat` output formats for shell scripts.

Git history debugging

Compare commit timestamps (author vs committer) and their exact string form for tooling tests.

Frequently Asked Questions

What is the systemd journal timestamp format?

Microseconds since epoch (e.g. `1786624200000000`), with µs resolution — the `_SOURCE_REALTIME_TIMESTAMP` field.

What is the DOS FAT timestamp format?

A 16-bit date + 16-bit time with 2-second granularity (bits: 7 year, 4 month, 5 day; 5 hour, 6 min, 5 sec/2).

What is the Mac HFS timestamp?

Seconds since 1904-01-01 00:00:00 (the Mac epoch), stored as unsigned 32-bit — it wraps in 2040.

What is the POSIX touch format?

`[[CC]YY]MMDDhhmm[.ss]` — e.g. `2608131430.00` for 2026-08-13 14:30. Also accepts `@epoch` seconds.

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All Format Guides

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