Time Converter
Add, subtract, and convert between time units. Calculate durations and time differences with precision.
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Understanding Time Units
Seconds
The base unit of time in the International System of Units (SI). Defined by the radiation frequency of cesium atoms.
Minutes
60 seconds make a minute. The minute is accepted for use with SI units but is not an SI unit itself.
Hours
60 minutes or 3,600 seconds. Used worldwide for timekeeping and dividing the day.
Days
24 hours or 1,440 minutes. A day is the time it takes Earth to complete one rotation on its axis.
Weeks
7 days. A week is a cultural convention with roots in ancient calendars and religious traditions.
Key Conversions
1 minute = 60 seconds
1 hour = 3,600 seconds
1 day = 86,400 seconds
1 week = 604,800 seconds
Time Conversion Formulas
- Seconds to Minutes: minutes = seconds ÷ 60
- Minutes to Seconds: seconds = minutes × 60
- Hours to Minutes: minutes = hours × 60
- Days to Hours: hours = days × 24
- Weeks to Days: days = weeks × 7
- Days to Seconds: seconds = days × 86,400
Time Converter Questions & Answers
Why are there 60 seconds in a minute and 60 minutes in an hour?
The sexagesimal (base-60) system originated with the ancient Sumerians around 2000 BCE. It was adopted by the Babylonians and later the Greeks and Arabs. The number 60 was chosen because it has many divisors (1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60), making calculations easier for fractions. This system was passed down through history and became the standard for measuring time.
How is a second defined scientifically?
Since 1967, the second has been defined by the International System of Units (SI) as exactly "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom." This atomic definition is incredibly precise, with atomic clocks accurate to within 1 second in 100 million years.
Why do we have leap seconds?
Leap seconds are occasionally added to Coordinated Universal Time (UTC) to account for irregularities in Earth's rotation. While atomic time (TAI) is perfectly regular, Earth's rotation is gradually slowing due to tidal friction and other factors. When the difference between atomic time and Earth's rotation time approaches 0.9 seconds, a leap second is added to keep UTC in sync with astronomical time (UT1). Since 1972, 27 leap seconds have been added.
What's the difference between solar time and atomic time?
Solar time is based on Earth's rotation and the position of the Sun in the sky. A solar day is the time between two successive passages of the Sun across the meridian. Atomic time is based on the precise vibrations of atoms (cesium-133) in atomic clocks. While solar time varies slightly due to Earth's irregular rotation, atomic time is perfectly uniform. UTC is a compromise that keeps atomic time in sync with solar time through leap seconds.