Satellite Time Converter

Supports mutual conversion between satellite time systems such as GPS, BeiDou, GLONASS, and Galileo and UTC and Julian Date, including week number and seconds-of-week calculations.

Bug report

Browser execution mode: Your data is processed in your browser and is not uploaded to the server.

Speed and Stability: Processing speed depends on your device and browser. For large batch work, the desktop version may be more stable.

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If the online tool fails to load or run, try the desktop tool.https://tools.yikeaigc.com/

Tool Usage

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Before converting single or batch entries, confirm leap seconds, precision, and batch rules in “Parameter Settings”. Sample data can be loaded to check the relationships between GPS, BeiDou, GLONASS, Galileo, and UTC.

Current UTC -- --

GPS seconds of week -- --

BeiDou seconds of week -- --

Leap second settings -- --

Conversion settings

Auto leap seconds are calculated from the built-in bulletin table; fixed and custom values both refer to the GPS-UTC offset in seconds.

GPS-UTC leap second offset The current IERS bulletin gives GPS-UTC as 18 seconds.

Custom GPS-UTC offset For historical recomputation or special ephemeris scenarios.

Decimal seconds Calculations use milliseconds; 6 digits will be padded for display.

Batch record reading For GPS week + seconds of week, use one entry per line.

Batch output fields Full fields include TAI, GLONASS, JD, and MJD.

Error row handling The preview always shows error tips.

Common references

Quickly check epochs and current second offsets for satellite time systems.

Tip: Load a reference point first to quickly check week, seconds of week, and Julian day results.

Enter time

Select an input type and enter its parameters. Date inputs are interpreted in the selected system time scale.

Input time type

Unix timestamp unit

Year

Months

Day

Time

Minutes

sec

Week number

Seconds of week SOW

GPS week rollover countUse when entering GPS week 0-1023.

Year

Day of year DOY

Time

Minutes

sec

Modified Julian Date MJD

Unix timestamp

UTC and date numbers

UTC time: --
Unix seconds: --
Unix milliseconds: --
Day of year / Weekday: --
JD / MJD: --

GPS time (GPST)

GPS time: --
GPS week number: --
Seconds of week / Day of week: --
Week rollover: --
GPS-UTC: --

BeiDou time (BDT)

BDT time: --
BDT week number: --
Seconds of week / Day of week: --
BDT-UTC: --
GPS-BDT: --

Galileo time (GST)

GST time: --
GST week number: --
Seconds of week / Day of week: --
GST-UTC: --

GLONASS time

GLONASS time: --
Four-year cycle N4: --
Day in cycle NA: --
Seconds of day: --

TAI and offset

TAI time: --
TAI-UTC: --
TAI-GPS: --
TAI MJD: --

Batch input

Paste text directly or select multiple TXT/CSV files; files are read and processed locally only.

Batch input type

Batch Unix unit

Text data

File data

Select or drop TXT/CSV files Multiple files supported. Only the first 20 are shown, but all files are processed.

Preview & download

Preview shows up to the first 20 records; CSV and ZIP downloads include all converted results.

Batch results will appear here. Set parameters, then paste text or select files and start processing.

Total records0

Success0

Errors0

Files0

Instructions

Software Usage Instructions

Select conversion mode: The tool provides two modes: "Single Conversion" and "Batch Conversion". Click the corresponding tab to switch based on your needs.
Select the input time type:
- UTC Time: Coordinated Universal Time; enter year, month, day, hour, minute, and second
- GPS Time: GPS satellite system time
- BeiDou Time (BDT): BeiDou Navigation Satellite System time
- GPS Week + Seconds of Week: Enter the GPS week number, seconds of week, and number of week rollovers
- BDT Week + Seconds of Week: Enter the BeiDou week number and seconds of week
- Modified Julian Date (MJD): Number of days since November 17, 1858
- Julian Date (JD): Continuous count of days since 4713 BC
- Unix Timestamp: Number of seconds since January 1, 1970
Configure leap second parameters:
- Automatic calculation: Automatically looks up and determines the leap second value based on the input time (recommended)
- Fixed value: Select a fixed leap second value (18 seconds applies from 2017 to the present)
- Custom: Manually enter the leap second value
Enter time data: Fill in the time value in the corresponding input field based on the selected type. You can click "Use Current Time" to automatically fill in the system's current UTC time, or click "Load Example" to fill in sample data.
Run conversion: Click the "Start Conversion" button, and the system will calculate and display conversion results for six major time systems, including UTC, GPS, BeiDou, GLONASS, Galileo, and International Atomic Time (TAI).
Batch conversion: Switch to the "Batch Conversion" tab and enter one time value per line. Multiple formats are supported. After processing is complete, you can copy the results or download a CSV/ZIP file.

FAQ

A: GPS time started at 00:00:00 UTC on January 6, 1980. It is a continuous time scale and does not include leap second adjustments. UTC time periodically adds leap seconds to coordinate the difference between atomic time and Earth's rotation time. As of 2024, GPS time is 18 seconds ahead of UTC time.

A: The GPS system uses a 10-bit binary number to represent the week number, ranging from 0 to 1023, for a total of 1024 weeks. When the week number reaches 1023, it starts counting again from 0; this is called a "week rollover." The first rollover occurred on August 21, 1999, and the second occurred on April 6, 2019. When entering a GPS week number, you need to specify the number of rollovers to determine the correct time.

A: BeiDou Time (BDT) starts from 00:00:00 UTC on January 1, 2006. Like GPS time, BDT is represented as week number + seconds of week, but it has a different start time. Because BDT starts later (about 26 years after GPS), the BDT week number is about 1356 weeks smaller than the GPS week number at the same moment.

A: A leap second is a one-second adjustment introduced to coordinate the difference between atomic time and Earth's rotational time. Because the Earth's rotation speed is not uniform, one second needs to be periodically added to or subtracted from UTC. GPS time does not include leap seconds, so the difference between GPS time and UTC increases as leap seconds accumulate. Accurate time conversion must handle leap seconds correctly.

A: Julian Date (JD) is a continuous count of days starting at noon on January 1, 4713 BC, and its value is relatively large. Modified Julian Date (MJD) equals JD minus 2400000.5, meaning it starts counting from midnight on November 17, 1858; its value is smaller and easier to use. MJD is widely used in astronomy and satellite navigation.

A: Seconds of Week (SOW) refers to the number of seconds from the start of each week (Sunday 00:00:00) to the current moment, ranging from 0 to 604799. Day of Week (DOW) indicates which day of the week it is, with Sunday as 0 and Saturday as 6. There are 604800 seconds in a week (7 days × 24 hours × 3600 seconds).

A: Batch conversion supports four input formats: UTC time format (e.g., 2024-01-15 12:30:45), GPS week number + seconds of week format (e.g., 2295,133845), Modified Julian Date format (e.g., 60324.52148), and Unix timestamp format (e.g., 1705322445). Enter one time value per line, and you can choose different delimiters.