Epoch timestamp converters, world timezone clocks, ISO 8601 parsers, and cron schedule builders.
Convert Microsoft Excel 1900 date system serial integers into standard ISO 8601 timestamps.
Calculate continuous Julian Day Numbers (JDN) and Modified Julian Date (MJD) from Gregorian dates.
Convert high-precision 19-digit nanosecond timestamps into formatted UTC strings.
Check exact clock shift dates and hour offsets for US, EU, and global timezones.
Build valid ISO 8601 duration expressions for scheduling APIs and calendar standards.
Find your Chinese zodiac animal and elemental polarity from birth year.
Calculate cumulative 37-second leap second offsets between UTC, TAI, and GPS time.
Convert calendar dates to ISO 8601 week formats (e.g. 2026-W35-6 for Saturday).
Calculate calendar and custom fiscal year quarters starting in any month (e.g. Feb, July, Oct).
Convert clock in/out minutes to standard payroll decimal hours (15-min / 6-min increments).
Convert time durations between Milliseconds (ms), Seconds (s), Hours (hr), and Days.
Calculate current lunar illumination percentage and moon phase for any date.
Calculate the exact completion date after adding N business days (skipping weekends).
Convert Gregorian calendar dates into astronomical Julian Day Numbers (JDN).
Calculate exact calendar dates for Spring/Autumn Equinox and Summer/Winter Solstice.
Calculate total calendar days, weekends, and Monday-Friday business days.
Find mutual working hour overlap windows across international timezones.
Calculate billable and working hours per year (2,080 standard) factoring in holidays & PTO.
Calculate solar noon transit time and daylight hours for any latitude.
Convert epoch timestamps (seconds & ms) into UTC, GMT, and ISO 8601 strings.
Calculate start and end dates for Q1, Q2, Q3, and Q4 across calendar & fiscal years.
Calculate the exact ISO 8601 week number (Week 1 to Week 53) for any date.
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