Time Conversion Calculator
Choose the input unit you have and the output unit you want to convert to. Enter the value you want to convert then click on the "Calculate" button. All results are rounded to 3 decimal places.
* Months in this conversion calculator are calculated at 30.41666 days/month since this is the value of 365 days/year divided by 12 months/year.
** Years in this conversion calculator are calculated at 365 days/year. This calculator does not factor in leap years which are 366 days/year.
"Sidereal day: a unit of time used in astronomy, equal to the period of time in which the earth makes one rotation relative to the stars. If we could view the earth from outside the Solar System, we would see that it actually completes 366.242 rotations during one year (one revolution around the sun). We only count 365.242 because one rotation is cancelled out for us by our tour around the sun. Thus the sidereal day, the average interval between two successive risings of the same star, is shorter than the mean solar day (see day) by 1/366.242. The sidereal day equals 23 hours 56 minutes 4.090 54 seconds, or 86 164.090 54 seconds. Like the regular day it is divided into 24 sidereal hours, each sidereal hour being divided into 60 sidereal minutes and each sidereal minute into 60 sidereal seconds. The sidereal hour equals 59 minutes 50.17 seconds; the sidereal minute equals 59.8362 seconds, and the sidereal second equals 0.997 270 second. Traditionally, observatories had clocks set to this sidereal cycle, and astronomers still use sidereal time in making telescope settings."
How to Convert Units of Time
Conversions are performed by using a conversion factor. By knowing the conversion factor, converting between units can become a simple multiplication problem:
S * C = E
Where S is our starting value, C is our conversion factor, and E is our end converted result.
To simply convert from any unit into seconds, for example, from 120 minutes, just multiply by the conversion value in the right column in the table below.
120 min * 60 [ (s) / (min) ] = 7200 s
To convert from seconds into units in the left column divide by the value in the right column or, multiply by the reciprocal, 1/x.
7200 s / 60 [ (s) / (min) ] = 120
To convert among any units in the left column, say from A to B, you can multiply by the factor for A to convert A into s then divide by the factor for B to convert out of s. Or, you can find the single factor you need by dividing the A factor by the B factor.
For example, to convert from minutes to hours you would multiply by 60 then divide by 3600. Or, multiply by 60/3600 = 0.0166666666666667. So, to convert directly from min to hr you multiply by 0.0166666666666667.
( s )
( s / Unit )
References/ Further Reading
The National Institute of Standards and Technology (NIST) - The NIST Guide for the use of the International System of Units - Appendix B, subsections B.8 Factors for Units Listed Alphabetically and B.9 Factors for units listed by kind of quantity or field of science.
Lide, David R., Daniel (Editor-in-Chief). CRC Handbook of Chemistry and Physics, 89th Edition, New York, NY: CRC Press, p. 1-28, 2008.
Wikipedia contributors. "Conversion of units" Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, last visited 26 Jun. 2011.
How Many? A Dictionary of Units of Measurement at http://www.unc.edu/~rowlett/units/
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