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Chrome & WebKit Timestamp Converter. Microseconds Since 1601

Several Chromium and WebKit internals store time as microseconds since January 1, 1601, the Windows FILETIME epoch. If you have a 16-digit value out of a browser database, this is the tool that reads it.

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Chrome & WebKit time → dates.

Chromium's Date.now() and WebKit's Date.getTime() historically returned microseconds since 1601 (the same epoch as Windows FILETIME.

Where these values come from

The WebKit epoch (1601-01-01) is the same reference Windows uses for FILETIME, Chromium adopted it for a handful of internal clocks, notably the last_visit_time and cookie timestamp columns in the old Chrome SQLite databases, so forensics and data-recovery tools regularly meet 16-digit values like 13430534400000000 that are neither Unix seconds nor ticks.

The conversion is: Unix time = value / 1,000,000 − 11,644,473,600 seconds. Divide the microseconds to seconds, subtract the 1601→1970 gap. The "Now" button shows the current instant in the same format.

Cookie values and history rows, decoded

  • 13430534400000000 µs since 1601 → Aug 7, 2026 00:00:00 UTC — divide by 1e6 (13,430,534,400 s), subtract 11,644,473,600 → Unix 1,786,060,800.
  • 12812083200000000 → Jan 1, 2007 00:00:00 UTC, the classic "start of 2007" probe value used in browser-forensics write-ups.
  • Aug 7, 2026 12:00:00 UTC → 13430577600000000 µs — the reverse direction, plus the equivalent 100ns FILETIME ticks (134305776000000000).

FILETIME, WebKit, and .NET, one family

Windows FILETIME counts 100-nanosecond ticks since 1601; WebKit counts microseconds since 1601, exactly ten times coarser. Both are handled here: every output row shows the value as µs and as 100ns ticks, so a value from either world converts in the same box. The LDAP / Active Directory converter covers the same 1601 epoch for Active Directory attributes.

Gotchas: µs vs ms, pre-1601 dates, and column context

  • µs, not ms. One extra decimal place is easy to miss. A value that decodes to year 292 million instead of 2026 is in milliseconds, the converter flags values out of the sane range.
  • Not the .NET ticks epoch.NET counts 100ns ticks since year 1, so values are ~621 trillion ticks larger. Different constant, different converter — use the .NET ticks converter.
  • Column context matters. The same column family appears in cookies, history, and downloads; always confirm which field you read before trusting the date.

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Sources & references

Same family, other members

WebKit microseconds sit inside a whole family of epoch offsets. The neighboring formats:

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