Windows FileTime / LDAP Timestamp Converter
Convert Windows FileTime and Active Directory attributes like pwdLastSet or lastLogon to readable dates.
FileTime ⇄ Timestamp
Runs entirely in your browserType in either field — the other updates live.
Uses BigInt internally — regular JavaScript numbers lose precision above 253, which FileTime values exceed today.
What is Windows FileTime?
Windows FileTime counts 100-nanosecond intervals since January 1, 1601, 00:00:00 UTC. It's used throughout the Windows API, NTFS file metadata, and LDAP/Active Directory attributes such as pwdLastSet, lastLogon, and accountExpires.
The 1601 epoch was chosen because it starts the first 400-year Gregorian calendar cycle — an implementation convenience, not anything meaningful about that date itself.
- 100-nanosecond intervals since January 1, 1601 UTC
- Same tick granularity as .NET ticks, different epoch
- Used in NTFS timestamps and Active Directory attributes
- Offset from Unix epoch: 116,444,736,000,000,000 (100ns units)
FileTime Format
Subtract 116,444,736,000,000,000 and divide by 10,000 to get Unix milliseconds.
How do I convert an Active Directory timestamp like pwdLastSet to a date?
Paste the raw integer value from the LDAP attribute into the converter above. It subtracts the FileTime-to-Unix epoch offset and converts to a readable date, using BigInt math to stay precise.
Frequently Asked Questions
pwdLastSet, lastLogon, lastLogonTimestamp, accountExpires), all stored as raw 64-bit FileTime integers.
0 in fields like lastLogon or pwdLastSet means "never" \u2014 it\u2019s a sentinel, not a literal 1601 date. This converter will still compute 1601-01-01 for a literal 0, so treat that result as "not set" in an LDAP context.
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