GPS Time Converter
Convert between UTC, GPS week/second-of-week, Julian date, and Unix timestamp for satellite data processing.
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About GPS time and its conventions
GPS time is the atomic time scale broadcast by GPS satellites. It started at midnight January 6, 1980 (UTC) and has not included any leap seconds since. As a result, GPS time is currently 18 seconds ahead of UTC (as of 2024) because UTC has added 18 leap seconds since 1980.
GPS time is typically expressed as a pair (GPS week, second-of-week). The week counter rolls over every 1024 weeks (about 19.6 years); legacy receivers had to be updated for the 2019 rollover. Most modern receivers use the extended 13-bit week number that does not roll over until 2137.
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gps_time.factors_title
- gps_time.factor_1
- gps_time.factor_2
- gps_time.factor_3
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- gps_time.factor_6
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- gps_time.dop_1 \u2014
- gps_time.dop_2 \u2014
- gps_time.dop_3 \u2014
- gps_time.dop_4 \u2014
- gps_time.dop_5 \u2014
When you need GPS time conversions
RINEX file processing: observation files are timestamped in GPS time; you need to convert for comparison with UTC logs.
Almanac and ephemeris analysis: satellite orbital data files reference GPS week/SOW.
Time-stamped coordinate solutions: precise point positioning (PPP) services output results tagged with GPS time.
Multi-sensor synchronization: when fusing GNSS with IMU or cameras, you need consistent time conversion.
Frequently asked questions
Why does GPS time differ from UTC?
GPS time does not include leap seconds, while UTC does. Since GPS started in 1980 and UTC has added 18 leap seconds since then, GPS is currently 18 seconds ahead.
What is the GPS week rollover?
The original 10-bit GPS week counter wraps every 1024 weeks. This happened in 1999 and 2019. Modern GPS uses 13 bits (8192 weeks = 157 years).
How precise is GPS time?
GPS satellites broadcast time with nanosecond precision. Disciplined receivers can lock to GPS time at the 10-nanosecond level.
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Related references
For more on GPS and satellite time systems, see our glossary entries on GPS, GNSS, and atomic time.