NTP Timestamp Converter
NTP timestamps count seconds since January 1, 1900 UTC in a 64-bit fixed-point format: 32 bits of seconds + 32 bits of fraction (about 232 picoseconds resolution). NTP packets, PTP (IEEE 1588) and SNTP exchange this representation.
This converter renders your date-time as the decimal NTP seconds, the 64-bit NTP value, and the 32-bit hex form so you can decode packet captures or generate test vectors.
NTP Timestamp Converter Quick Reference
| Format | Pattern / Description | Example 1 | Example 2 |
|---|---|---|---|
| NTP Timestamp | Seconds since 1900 | 3995620200 | 3976214400 |
| NTP 64-bit Hex | RFC 5905 | EE285368.00000000 | ED003780.00000000 |
* Examples are rendered in UTC for the fixed sample instants above.
When to Use NTP Timestamp
Packet capture analysis
Wireshark shows NTP timestamps as raw hex/seconds-since-1900. Convert capture values to wall-clock time when debugging clock skew.
PTP/SNTP development
Generate NTP-format test vectors from known UTC times for protocol implementations and test harnesses.
Clock synchronization audits
Verify the NTP time your device reports corresponds to the expected UTC instant, including the 1900 vs 1970 epoch difference.
Frequently Asked Questions
What is an NTP timestamp?
Seconds since 1900-01-01 00:00:00 UTC in 64-bit fixed point: upper 32 bits = integer seconds, lower 32 bits = fraction. It wraps every 136 years (2036).
What is the difference between NTP and Unix timestamps?
Epoch: NTP counts from 1900, Unix from 1970 (difference 2,208,988,800 s). Resolution: NTP is 64-bit fixed point; Unix is usually integer seconds or ms.
What is the 2036 NTP rollover?
The 32-bit seconds field wraps in February 2036. NTPv4 mitigates with the era concept, but older software may misinterpret dates after rollover.
How do I read the 64-bit hex NTP value?
The first 8 hex digits are seconds since 1900, the last 8 are the fraction of a second. `e.g. 0xDC8B2B41_80000000` = seconds 3,700,000,000 + 0.5 s.
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