Time Conversion Matrix

Time is one of the seven base SI quantities, with the second defined since 1967 by the cesium-133 atomic transition (9,192,631,770 periods of radiation). Modern atomic clocks keep time to a few parts in 10¹⁸. This converter handles standard time units from nanoseconds to centuries: SI second and its multiples (millisecond, microsecond, nanosecond), traditional time units (minute = 60 s, hour = 3,600 s, day = 86,400 s), calendar units (week = 7 days, month average 30.44 days, year = 365.25 days using the Julian definition), and historical periods (decade = 10 years, century = 100 years). The base-60 system for minutes and hours descends from ancient Babylonian sexagesimal arithmetic. Use time conversion for scientific research, astronomy, computing benchmarks, network latency, project planning, age calculations, and historical analysis. Atomic time and Earth rotation occasionally diverge, requiring leap seconds to be added (a practice ending by 2035).

• ✓The second is the only SI base unit of time. Longer units (minute, hour, day) are all defined in seconds.
• ✓A month is ambiguous: calendar months range from 28 to 31 days. For calculations use 30.44 days (year ÷ 12).
• ✓A year in daily life is 365 days, but astronomers and engineers use 365.25 days (the Julian year) to account for leap years.
• ✓Millisecond (ms) and microsecond (µs) are essential in networking and computing — but quickly diverge in everyday conversation.

• ✗Assuming a month is always 30 days — January has 31, February has 28/29.
• ✗Confusing seconds of time with seconds of angle (both use "s" abbreviation).
• ✗Converting years to days with 360 (financial convention) instead of 365.25 (physical).
• ✗Using calendar months for precise durations — use days for accuracy.