Time (symbolized by t) is the continuous, irreversible sequence of existence and events progressing from the past through the present into the future. Across project scheduling, software programming, telecommunications, satellite navigation (GPS), quantum physics, and astronomy, precise time measurement relies on two distinct measurement frameworks: International System of Units (SI metric sub-multiples derived from the Atomic Second: Milliseconds, Microseconds, Nanoseconds, Attoseconds, Planck Time) and traditional calendar / astronomical cycles (Minutes, Hours, Days, Weeks, Fortnights, Synodic Months, Julian / Tropical Years, Sidereal Days, Decades, Centuries, Millennia).
Our free online Time Converter provides instant, high-precision conversions across all atomic, metric, chronological, calendar, and astronomical time duration units:
- Minutes to Hours (min to h): Divide minutes by
60(1 hour = 60 min = 3,600 s = 0.041667 days). - Hours to Days (h to d): Divide hours by
24(1 solar day = 24 h = 1,440 min = 86,400 s). - Days to Seconds (d to s): Multiply days by
86,400(1 Julian year = 365.25 d = 31,557,600 s). - Seconds to Milliseconds (s to ms): Multiply seconds by
1,000(1 s = 1,000 ms = 1,000,000 μs = 109 ns). - Solar Day vs. Sidereal Day:
1 Sidereal Day = 23 hours, 56 minutes, 4.0905 seconds (86,164.09 s)relative to distant fixed stars. - Planck Time (Quantum Limit):
1 Planck Time (tP) = 5.39124 × 10-44 seconds(the smallest physically meaningful unit of time).
Master Time & Duration Unit Conversion Table
The table below displays exact physical definitions, SI multipliers, and day/second equivalents relative to 1 SI Second (defined by 9,192,631,770 Cesium-133 atomic transition periods):
| Time Unit Name | Symbol | Exact Value in Seconds (s) | Minute, Hour & Day Equivalent | Domain & System Standard |
|---|---|---|---|---|
| 1 Second | s |
1.0 s (9,192,631,770 Cesium-133 cycles) |
0.016667 min (0.000278 h / 0.00001157 days) | SI Base Fundamental Unit of Time |
| 1 Millisecond | ms |
0.001 s (10-3 s) | 0.00001667 min (1,000 μs / 1,000,000 ns) | Computer Network Ping & Audio Latency |
| 1 Microsecond | μs |
1.0 × 10-6 s (10-6 s) | 0.001 ms (1,000 ns) | High-Frequency Trading & Microcontroller Timing |
| 1 Nanosecond | ns |
1.0 × 10-9 s (10-9 s) | 0.001 μs (1,000 ps / Light travels ~30 cm) | CPU RAM Memory Bus Clock Cycles |
| 1 Shake | shake |
1.0 × 10-8 s (10 ns) | 10.0 ns (0.01 μs) | Nuclear Physics Fission Generation Time |
| 1 Femtosecond | fs |
1.0 × 10-15 s (10-15 s) | 0.001 ps (1,000 as) | Ultrafast Laser Spectroscopy & Molecular Chemistry |
| 1 Attosecond | as |
1.0 × 10-18 s (10-18 s) | 0.001 fs (2023 Nobel Physics timescale) | Atomic Electron Orbital Motion Transition |
| 1 Planck Time | tP |
5.39124 × 10-44 s | (ℏG ÷ c5)1/2 | Quantum Gravity Minimum Meaningful Time |
| 1 Minute | min |
60.0 s (exact) |
0.016667 h (0.0006944 days) | Sumerian Sexagesimal Chronological Unit |
| 1 Hour | h, hr |
3,600.0 s (exact) |
60.0 min (0.041667 days / 1/24 day) |
Standard Work Shift & Flight Duration Unit |
| 1 Day (Mean Solar Day) | d, day |
86,400.0 s (exact) |
24.0 h (1,440.0 min / 0.142857 weeks) |
Earth Solar Diurnal Rotation Period |
| 1 Day (Sidereal) | d (sidereal) |
86,164.090530 s |
23 h 56 min 4.09 s (0.99727 solar days) | Earth Stellar Rotation relative to Fixed Stars |
| 1 Week | wk |
604,800.0 s |
7.0 days (168.0 h / 10,080.0 min) |
Standard Work Week & Payroll Schedule |
| 1 Fortnight | fortnight |
1,209,600.0 s |
14.0 days (2.0 weeks / 336.0 h) |
Bi-Weekly Payroll & UK Legal Period |
| 1 Synodic Month (Lunar Month) | month (synodic) |
2,551,443.84 s |
29.530589 days (708.734 h) | New Moon to New Moon Lunar Orbit Phase |
| 1 Year (Julian / Standard) | y, yr |
31,557,600.0 s |
365.25 days (8,766.0 h / 52.1785 weeks) |
Standard Astronomical & Financial Year |
| 1 Year (Tropical / Solar) | y (tropical) |
31,556,925.20 s | 365.242189 days (Vernal Equinox to Equinox) | Gregorian Calendar Equinox Seasons Cycle |
| 1 Decade | decade |
315,576,000.0 s | 10.0 years (3,652.5 days / 87,660.0 h) |
10-Year Epoch Period |
| 1 Century | century |
3.15576 × 109 s | 100.0 years (36,525.0 days) |
100-Year Historical Era |
Step-by-Step Duration Calculation Example
To convert an annual work duration of 2,080 Hours (2,080 h) (50 weeks × 40 h/week) into Days, Minutes, and Seconds:
2,080 Hours ÷ 24 = 86.6667 Days (86 days, 16 hours)
2,080 Hours × 60 = 124,800 Minutes
124,800 Minutes × 60 = 7,488,000 Seconds
Thus, a standard annual 2,080-hour work year equals 124,800 minutes (or 7,488,000 seconds / 86.67 full days).
Real-World Computer, Human & Astronomical Time Benchmarks
Below is a comparative reference chart showing time durations across CPU clock cycles, human eye blinks, Earth rotation, human lifespans, and cosmic history:
| Event / Phenomenon | Duration in Metric Units (ns / ms / s) | Duration in Calendar Units (Hours / Days / Years) | Physical & Computing Context |
|---|---|---|---|
| Modern 4 GHz Computer CPU Clock Cycle | 0.25 Nanoseconds (250 Picoseconds) | 2.89 × 10-14 days | Single clock period of a 4.0 GHz processor core |
| Human Eye Blink Average Duration | 100 to 400 Milliseconds (0.1 to 0.4 s) | 0.00116 to 0.00463 hours | Biological involuntary corneal lubrication reflex |
| Earth Stellar Sidereal Rotation Period | 86,164.09 Seconds | 23 Hours 56 Minutes 4.09 Seconds (0.99727 days) | 360° rotation of Earth relative to background stars |
| Average Global Human Lifespan (77.5 Years) | 2.445 × 109 Seconds (2,445,714,000 s) | 28,306.87 Days (679,365 Hours / 77.5 Julian Years) | Modern human actuarial life expectancy at birth |
| Age of the Universe Since Big Bang | 4.35 × 1017 Seconds | 13.787 Billion Years (1.3787 × 1010 years) | Cosmological time elapsed since the Big Bang origin |
History & Standards: Sumerian Sexagesimal Base-60 vs. 1582 Gregorian Reform vs. 1967 Atomic Second
Sumerian & Babylonian Sexagesimal System (c. 2000 BC)
Over 4,000 years ago in ancient Mesopotamia, Sumerian and Babylonian astronomers developed a base-60 (sexagesimal) numeral system to track celestial movements. They divided the day into 24 hours (12 daytime hours, 12 nighttime hours based on sundials), each hour into 60 minutes (pars minuta prima), and each minute into 60 seconds (pars minuta secunda). Base-60 was chosen because 60 is a highly composite number evenly divisible by 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30.
The 1582 Gregorian Calendar Reform
The ancient Roman Julian calendar (established by Julius Caesar in 45 BC) assumed a solar year length of exactly 365.25 days. However, the true tropical year is approximately 365.24219 days. Over 16 centuries, this 11-minute annual discrepancy caused the calendar to drift by 10 days relative to the vernal equinox. On October 4, 1582, Pope Gregory XIII instituted the Gregorian Calendar Reform, skipping 10 days (jumping to October 15) and modifying leap year rules so that century years are only leap years if divisible by 400 (e.g., 1600 and 2000 were leap years, but 1700, 1800, and 1900 were not).
The 1967 Cesium-133 Atomic Second Redefinition
Prior to 1967, the second was defined astronomically as 1 ÷ 86,400 of a mean solar day. However, tidal friction caused by Moon gravitation causes Earth’s rotation to gradually slow down unpredictably. In 1967, the 13th General Conference on Weights and Measures (CGPM) abandoned Earth rotation, defining the SI Second as the duration of exactly 9,192,631,770 periods of radiation corresponding to the transition between two hyperfine levels of the ground state of the Cesium-133 atom.
Popular direct conversions:
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Frequently Asked Questions (FAQ)
How many seconds are in 1 Solar Day?
There are exactly 86,400 seconds in 1 Mean Solar Day (24 hours × 60 minutes × 60 seconds).
How many hours are in 1 Julian Year?
There are exactly 8,766 hours in 1 Julian Year (365.25 days × 24 hours = 31,557,600 seconds).
What is the difference between a Solar Day and a Sidereal Day?
A Solar Day (24 hours = 86,400 s) is the time Earth takes to rotate relative to the Sun. A Sidereal Day (23 hours, 56 minutes, 4.09 seconds = 86,164.09 s) is the time Earth takes to rotate 360° relative to distant fixed stars. A sidereal day is about 3 minutes 56 seconds shorter because Earth moves along its orbit around the Sun.
What is Planck Time?
Planck Time (tP) is the theoretical minimum unit of time in quantum mechanics, equal to approximately 5.39124 × 10-44 seconds. It represents the time required for light to travel 1 Planck length.