Time

We use time to sequence events, to compare their durations and the intervals between them, and to quantify the speed at which objects move and things change.

To measure time, we can use anything that repeats itself regularly. One example is the start of a new day (as Earth rotates on its axis). Two more are the phases of the moon (as it orbits the Earth), and the seasons of the year (as the Earth orbits the Sun). Even in ancient times, people developed calendars to keep track of the number of days in a year. They also developed sundials that used the moving shadows cast by the sun through the day to measure times smaller than a day. Today, highly accurate clocks can measure times less than a billionth of a second. The study of time measurement is horology.

The SI (Systeme Internationale) unit of time is one second, written as s.

In Einsteinian physics, time and space can be combined into a single concept. See space-time continuum.

Units of time

  • 1 millennium = 10 centuries = 100 decades = 200 lustrums = 250 quadrenniums = 333.33 trienniums = 500 bienniums = 1,000 years
  • 1 century = 10 decades = 20 lustrums = 25 quadrenniums = 33.33 trienniums = 50 bienniums = 100 years
  • 1 decade = 2 lustrums = 2.5 quadrenniums = 3.33 trienniums = 5 bienniums = 10 years
  • 1 year = 12 months = 365 days (366 days in leap years)
  • 1 month = 4 weeks = 28 to 31 days
  • 1 fortnight = 2 weeks = 14 days
  • 1 week = 7 days
  • 1 day = 24 hours
  • 1 hour = 60 minutes
  • 1 minute = 60 seconds
  • 1 second = SI base unit of time
  • 1 millisecond = 1/1,000 second
  • 1 microsecond = 1/1,000,000 second
  • 1 nanosecond = 1/1,000,000,000 second
  • 1 picosecond = 1/1,000,000,000,000 of a second
  • 1 femtosecond = 1/1,000,000,000,000,000 of a second
  • 1 attosecond = 1/1,000,000,000,000,000,000 of a second
  • 1 Planck time = smallest measurable unit of time

Things to measure time

Other Languages
Afrikaans: Tyd
Alemannisch: Zeit
አማርኛ: ጊዜ
Аҧсшәа: Аамҭа
العربية: زمن
aragonés: Tiempo
অসমীয়া: সময়
asturianu: Tiempu
Atikamekw: Tipahikanicic
Avañe'ẽ: Ára
azərbaycanca: Zaman (fizika)
تۆرکجه: زامان
বাংলা: সময়
Bân-lâm-gú: Sî-kan
башҡортса: Ваҡыт
беларуская: Час
беларуская (тарашкевіца)‎: Час
български: Време
Boarisch: Zeid
བོད་ཡིག: དུས་ཚོད།
brezhoneg: Amzer
буряад: Саг хугасаа
català: Temps
Чӑвашла: Вăхăт
čeština: Čas
Chi-Chewa: Nthawi
chiShona: Nguva
Cymraeg: Amser
dansk: Tid
Deutsch: Zeit
eesti: Aeg
Ελληνικά: Χρόνος
emiliàn e rumagnòl: Tèimp
English: Time
эрзянь: Шка
español: Tiempo
Esperanto: Tempo
estremeñu: Tiempu
euskara: Denbora
فارسی: زمان
français: Temps
Frysk: Tiid
furlan: Timp
Gaeilge: Am
galego: Tempo
ГӀалгӀай: Ха
客家語/Hak-kâ-ngî: Sṳ̀-kiên
хальмг: Цаг
한국어: 시간
հայերեն: Ժամանակ
हिन्दी: समय
Ido: Tempo
Bahasa Indonesia: Waktu
interlingua: Tempore
íslenska: Tími
italiano: Tempo
עברית: זמן
Basa Jawa: Wektu
ಕನ್ನಡ: ಕಾಲ
ქართული: დრო
қазақша: Уақыт
Kiswahili: Wakati
Kreyòl ayisyen: Tan
Кыргызча: Убакыт
Latina: Tempus
latviešu: Laiks
Lëtzebuergesch: Zäit
lietuvių: Laikas
Ligure: Tempo
Limburgs: Tied
Livvinkarjala: Aigu
lumbaart: Temp
magyar: Idő
मैथिली: समय
македонски: Време
മലയാളം: കാലം
मराठी: काळ
Bahasa Melayu: Masa
Mìng-dĕ̤ng-ngṳ̄: Sì-găng
монгол: Хугацаа
မြန်မာဘာသာ: အချိန်
Nāhuatl: Cahuitl
Nederlands: Tijd
Nedersaksies: Tied
नेपाली: समय
नेपाल भाषा: ई (काल)
日本語: 時間
Nordfriisk: Tidj
Norfuk / Pitkern: Tiem
norsk: Tid
norsk nynorsk: Tid
Novial: Tempe
occitan: Temps
ଓଡ଼ିଆ: ସମୟ (କାଳ)
oʻzbekcha/ўзбекча: Vaqt
ਪੰਜਾਬੀ: ਸਮਾਂ
پنجابی: ویلا
پښتو: وخت
Patois: Taim
Piemontèis: Temp
Plattdüütsch: Tiet
polski: Czas
português: Tempo
Qaraqalpaqsha: Waqıt
română: Timp
Runa Simi: Mit'awi
русиньскый: Час
русский: Время
саха тыла: Кэм
ᱥᱟᱱᱛᱟᱲᱤ: ᱚᱠᱛᱚ
Scots: Time
Seeltersk: Tied
Sesotho sa Leboa: Nako
shqip: Koha
sicilianu: Tempu
සිංහල: කාලය
سنڌي: وقت
slovenčina: Čas (fyzika)
slovenščina: Čas
словѣньскъ / ⰔⰎⰑⰂⰡⰐⰠⰔⰍⰟ: Врѣмѧ
ślůnski: Czas
Soomaaliga: Wakhti
کوردی: کات
српски / srpski: Време
srpskohrvatski / српскохрватски: Vrijeme
Basa Sunda: Waktu
suomi: Aika
svenska: Tid
Tagalog: Panahon
தமிழ்: நேரம்
татарча/tatarça: Вакыт
తెలుగు: సమయం
ไทย: เวลา
тоҷикӣ: Замон
ᏣᎳᎩ: ᎢᏳᏩᎪᏗ
Türkçe: Zaman
Türkmençe: Wagt
українська: Час
اردو: وقت
Vahcuengh: Seizgan
vèneto: Tenpo
vepsän kel’: Aig
Tiếng Việt: Thời gian
Võro: Aig
文言:
Winaray: Oras (pisika)
吴语: 辰光
ייִדיש: צייט
Yorùbá: Àsìkò
粵語: 時間
Zazaki: Zeman
žemaitėška: Čiesos
中文: 时间