Reference converter
Convert 30 cited units of time, including scientific jargon, SI-prefixed seconds, old English spans, and deep-time scales.
Pick a source unit, enter an amount, and compare it across scientific, calendar, historical, and cosmological scales.
Base value
1 seconds
| Unit | Conversion | Seconds | Category | Source |
|---|---|---|---|---|
Planck time Natural-unit timescale built from h-bar, G, and c; often used as a Planck-scale reference, not as a stopwatch tick. | 1.854858 x 10^+43 | 5.391247 x 10^-44 | physics | NIST CODATA 2022 fundamental constants |
Jiffy (physics) Physics usage: the time light takes to travel one fermi, or femtometre, in vacuum. | 2.997925 x 10^+23 | 3.335641 x 10^-24 | physics | IUPAC Gold Book: fermi (1e-15 m) |
Yoctosecond SI-prefixed second using yocto-, the 10^-24 prefix. | 1.000000 x 10^+24 | 1.000000 x 10^-24 | si | BIPM SI prefixes |
Atomic time unit Atomic unit of time; historically comparable to the electron timescale in the Bohr model. | 4.134137 x 10^+16 | 2.418884 x 10^-17 | physics | NIST CODATA 2022 atomic unit of time |
Femtosecond SI-prefixed second using femto-, the 10^-15 prefix. | 1.000000 x 10^+15 | 1.000000 x 10^-15 | si | BIPM SI prefixes |
Picosecond SI-prefixed second using pico-, the 10^-12 prefix. | 1.000000 x 10^+12 | 1.000000 x 10^-12 | si | BIPM SI prefixes |
Svedberg Sedimentation time unit named for Theodor Svedberg; equal to 10^-13 seconds. | 1.000000 x 10^+13 | 1.000000 x 10^-13 | physics | NIST Guide to the SI, Appendix B.8 |
Jiffy (computing) Linux kernel time unit: one jiffy equals 1/HZ second; shown here as 100 Hz, while 60 Hz systems make it 1/60 s. | 100 | 0.01 | computing | Linux kernel Rust docs: Jiffies |
Shake Informal nuclear-physics unit from 'two shakes of a lamb's tail'; NIST lists it as 10^-8 seconds. | 1.000000 x 10^+8 | 1.000000 x 10^-8 | physics | NIST Guide to the SI, Appendix B.8 |
Nanosecond SI-prefixed second using nano-, the 10^-9 prefix. | 1.000000 x 10^+9 | 1.000000 x 10^-9 | si | BIPM SI prefixes |
Microsecond SI-prefixed second using micro-, the 10^-6 prefix. | 1.000000 x 10^+6 | 1.000000 x 10^-6 | si | BIPM SI prefixes |
Millisecond SI-prefixed second using milli-, the 10^-3 prefix. | 1,000 | 0.001 | si | BIPM SI prefixes |
Blink Approximate upper-end duration of a human eye blink; measured blinks commonly span about 100-300 ms. | 3.333333 | 0.3 | human | PNAS / PMC: Eye blinks as a visual processing stage |
Second SI base unit of time, defined through the fixed caesium-133 hyperfine transition frequency. | 1 | 1 | si | BIPM SI base unit: second |
Minute Accepted non-SI unit for use with the SI: 1 minute is 60 seconds. | 0.016667 | 60 | calendar | BIPM SI Brochure, Table 8 |
Hour Accepted non-SI unit for use with the SI: 1 hour is 60 minutes, or 3,600 seconds. | 2.777778 x 10^-4 | 3,600 | calendar | BIPM SI Brochure, Table 8 |
Day Accepted non-SI unit for use with the SI: 1 day is 24 hours, or 86,400 seconds. | 1.157407 x 10^-5 | 86,400 | calendar | BIPM SI Brochure, Table 8 |
Week Seven-day civil calendar span recognized by NIST as a common time interval. | 1.653439 x 10^-6 | 604,800 | calendar | NIST Guide to the SI, Chapter 5 |
Fortnight From Old English for 'fourteen nights'; still common in British English and uncommon in American English. | 8.267196 x 10^-7 | 1.209600 x 10^+6 | historical | Merriam-Webster: fortnight |
Month Average Gregorian calendar month used for conversion only: 365.2425 days divided by 12. | 3.802649 x 10^-7 | 2.629746 x 10^+6 | calendar | U.S. Naval Observatory: Leap Years |
Year Mean Gregorian calendar year across the 400-year leap cycle: 365.2425 days. | 3.168874 x 10^-8 | 3.155695 x 10^+7 | calendar | U.S. Naval Observatory: Leap Years |
Lustrum Roman purification after the census; later a five-year period, with Pliny using lustrum as a span reference. | 6.337748 x 10^-9 | 1.577848 x 10^+8 | historical | Pliny, Natural History 7.49 via Attalus |
Olympiad Official Olympic term for a period of four consecutive calendar years. | 7.922185 x 10^-9 | 1.262278 x 10^+8 | historical | Olympic Charter, IOC Olympic World Library |
Decade A ten-year span; from Greek dekas, a group of ten. | 3.168874 x 10^-9 | 3.155695 x 10^+8 | calendar | Merriam-Webster: decade |
Score A tally of twenty; Lincoln's 'four score and seven years ago' counts 87 years. | 1.584437 x 10^-9 | 6.311390 x 10^+8 | historical | NPS: Gettysburg Address |
Century A one-hundred-year span; from Latin centum, hundred. | 3.168874 x 10^-10 | 3.155695 x 10^+9 | calendar | Merriam-Webster: century |
Millennium A one-thousand-year span; from Latin mille, thousand. | 3.168874 x 10^-11 | 3.155695 x 10^+10 | calendar | Merriam-Webster: millennium |
Megaannum Geologic-time unit abbreviated Ma: one million years, commonly used for ages on geologic time scales. | 3.168874 x 10^-14 | 3.155695 x 10^+13 | geology | Geological Society of America geologic time scale |
Gigaannum Geologic-time unit abbreviated Ga: one billion years, used for deep-time ages. | 3.168874 x 10^-17 | 3.155695 x 10^+16 | geology | Geological Society of America geologic time scale |
Hubble time Approximate inverse of the present Hubble constant; close to, but not identical with, the universe's age. | 2.200607 x 10^-18 | 4.544201 x 10^+17 | cosmology | NASA: Hubble Constant and Tension |
Calendar conversions use the mean Gregorian year of 365.2425 days; month is shown as one twelfth of that year. Variable real-world months and leap years are deliberately normalized for comparison.
A second is excellent for ordinary clocks, but science often needs scales that are far outside ordinary perception. A nuclear physicist can say a chain-reaction step takes a shake instead of repeatedly writing 10 nanoseconds. A chemist or physicist can use a jiffy for the time light crosses a nuclear length scale. At the extreme, Planck time is not a practical measured interval; it is a natural scale made from fundamental constants, useful when gravity and quantum mechanics collide.
Human language kept other units because institutions kept using them. Lustrum survived from the Roman census and purification ceremony into English as a five-year span. Score survived as a tally word for twenty, made famous to many readers by Lincoln's "four score and seven years ago." Fortnight is older still: literally fourteen nights. It remains normal in British and some Commonwealth English, but American English usually says "two weeks," so the word sounds increasingly literary or imported to U.S. readers.
The table keeps these mixed traditions honest by reducing each unit to seconds and linking its source. SI prefixes come from BIPM; CODATA constants come from NIST; geological Ma and Ga follow GSA time-scale usage; cultural terms cite dictionaries or primary historical texts.
Sources include BIPM SI prefixes, NIST unit factors, and 30 per-row citations in the converter.