TimeConverter
Instantly convert time units including Millisecond, Second, and more.
About Time Units
Time is a fundamental physical dimension measuring the progression and ordering of events. The SI base unit is the second, originally defined as 1/86,400 of a mean solar day, then redefined in 1967 as exactly 9,192,631,770 oscillations of the radiation emitted by a cesium-133 atom at rest at 0 K. Larger calendar units — minutes, hours, days, weeks, months, and years — are derived from this base with increasing levels of approximation. A year averages 365.25 days (31,557,600 s) to account for leap years; a month averages 30.4375 days (2,629,800 s).
The history of time measurement is one of humanity's oldest intellectual pursuits. The Babylonians (circa 2000 BCE) divided the day into 24 hours and each hour into 60 minutes — a base-60 (sexagesimal) system still embedded in our clocks. Mechanical clocks appeared in Europe in the 13th century, and pendulum clocks in the 17th century achieved accuracy to about 10 seconds per day. John Harrison's marine chronometers (1730s–70s) brought timekeeping to sea with enough accuracy to determine longitude. Quartz oscillators (1920s) and atomic clocks (1950s–60s) then pushed precision to levels unimaginable to earlier generations. Today's cesium atomic fountain clocks are accurate to about 1 second in 300 million years.
In practice, time unit conversions arise in fields ranging from software engineering to project management to astronomy. Computing deals in milliseconds and nanoseconds for performance profiling — a modern CPU can execute one billion instructions per second. Medical dosing intervals are specified in hours or days. Construction contracts set deadlines in weeks and months. Astronomers measure stellar distances in light-years and describe orbital periods in days or years. Understanding how to move fluently between milliseconds, seconds, minutes, hours, days, weeks, months, and years is indispensable for scheduling, science, and communication.
Common Time Conversions
| From | To |
|---|---|
| 1 minute | 60 seconds |
| 1 hour | 3,600 seconds — 60 minutes |
| 1 day | 86,400 seconds — 24 hours |
| 1 week | 604,800 seconds — 7 days |
| 1 month (avg) | 2,629,800 seconds — 30.44 days |
| 1 year (avg) | 31,557,600 seconds — 365.25 days |
| 1 millisecond | 0.001 seconds |
| 1 microsecond | 0.000001 seconds = 1,000 ns |
| 1 hour | 3,600 s — 60 min — 1/24 day |
| 1 year | 8,766 hours — 525,960 minutes |
| 1 decade | 10 years — 3,652.5 days |
| 1 century | 100 years — 36,524.25 days |
| 1 day | 1,440 minutes — 24 hours |
| 1 fortnight | 14 days — 336 hours — 1,209,600 s |
| 1 week | 7 days — 168 hours — 10,080 minutes |
Frequently Asked Questions
86,400 seconds: 24 hours × 60 minutes × 60 seconds.
Approximately 8,766 hours in an average Gregorian year (365.25 days × 24 h). A common year (365 days) has 8,760 hours; a leap year has 8,784 hours.
Earth takes about 365.2422 days to orbit the Sun. We add a leap day every 4 years (with century and 400-year corrections) to keep the calendar aligned with the solar year. This averages to 365.2425 days per year in the Gregorian calendar, very close to the true solar year.
A fortnight is exactly 2 weeks — 14 days or 1,209,600 seconds. The term is common in the UK and Australia.
A Gregorian year averages 31,557,600 seconds (365.25 × 86,400). A common year has 31,536,000 s; a leap year has 31,622,400 s.
This convention descends from ancient Babylonian mathematics, which used a base-60 (sexagesimal) number system. Sixty was chosen because it has many divisors (1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60), making it easy to divide into halves, thirds, quarters, and fifths without fractions.
A leap year has 366 days (February has 29 instead of 28). The rule: a year is a leap year if divisible by 4, EXCEPT centuries are not leap years unless also divisible by 400. So 2000 was a leap year; 1900 was not; 2024 is.
A common year contains 52 weeks plus 1 day (365 ÷ 7 = 52.143). A leap year contains 52 weeks plus 2 days. This is why the day of the week on which a date falls shifts by 1 (or 2 in a leap year) each year.