Date to GPS week and seconds converter
Useful for processing navigation data and setting survey gear or receivers that expect GPS time.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter date, time, seconds and time zone of the date entered.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
GPS seconds = (Unix seconds - 315964800) + leap seconds. Week = floor(GPS seconds / 604800) and seconds of week is the remainder. 10-bit week = week mod 1024.
Example
Inputs: Date = 2026-10-01, Time = 00:00, Seconds = 0, Time zone of the date entered = UTC. Result: GPS week: 2438; GPS minus UTC (leap seconds): 18.
Limits and caveats
- The leap second table runs to 2016-12-31, and none has been added since as of 2026.
- The leap second 23:59:60 itself cannot be entered.
Questions about this tool
When did GPS time start?
At midnight UTC on 6 January 1980, the start of week 0.
How many seconds are in a GPS week?
604800. Seconds of week restart at 0 at midnight between Saturday and Sunday in GPS time.
Why does a week start show 18 seconds at UTC midnight?
GPS time is 18 seconds ahead of UTC, so at UTC midnight the GPS week began 18 seconds earlier.