How many hours in 21 minutes?

Conversion formula

The conversion factor from minutes to hours is 0.016666666666667, which means that 1 minute is equal to 0.016666666666667 hours:

1 min = 0.016666666666667 hr

To convert 21 minutes into hours we have to multiply 21 by the conversion factor in order to get the time amount from minutes to hours. We can also form a simple proportion to calculate the result:

1 min → 0.016666666666667 hr

21 min → T_(hr)

Solve the above proportion to obtain the time T in hours:

T_(hr) = 21 min × 0.016666666666667 hr

T_(hr) = 0.35 hr

The final result is:

21 min → 0.35 hr

We conclude that 21 minutes is equivalent to 0.35 hours:

21 minutes = 0.35 hours

Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 hour is equal to 2.8571428571429 × 21 minutes.

Another way is saying that 21 minutes is equal to 1 ÷ 2.8571428571429 hours.

Approximate result

For practical purposes we can round our final result to an approximate numerical value. We can say that twenty-one minutes is approximately zero point three five hours:

21 min ≅ 0.35 hr

An alternative is also that one hour is approximately two point eight five seven times twenty-one minutes.

Conversion table

minutes to hours chart

For quick reference purposes, below is the conversion table you can use to convert from minutes to hours

minutes (min)	hours (hr)
22 minutes	0.367 hours
23 minutes	0.383 hours
24 minutes	0.4 hours
25 minutes	0.417 hours
26 minutes	0.433 hours
27 minutes	0.45 hours
28 minutes	0.467 hours
29 minutes	0.483 hours
30 minutes	0.5 hours
31 minutes	0.517 hours

Conversion units

The units involved in this conversion are minutes and hours. This is how they are defined:

Minute

The minute is a unit of time or of angle. As a unit of time, the minute (symbol: min) is equal to 1⁄60 (the first sexagesimal fraction) of an hour, or 60 seconds. In the UTC time standard, a minute on rare occasions has 61 seconds, a consequence of leap seconds (there is a provision to insert a negative leap second, which would result in a 59-second minute, but this has never happened in more than 40 years under this system). As a unit of angle, the minute of arc is equal to 1⁄60 of a degree, or 60 seconds (of arc). Although not an SI unit for either time or angle, the minute is accepted for use with SI units for both. The SI symbols for minute or minutes are min for time measurement, and the prime symbol after a number, e.g. 5′, for angle measurement. The prime is also sometimes used informally to denote minutes of time. In contrast to the hour, the minute (and the second) does not have a clear historical background. What is traceable only is that it started being recorded in the Middle Ages due to the ability of construction of "precision" timepieces (mechanical and water clocks). However, no consistent records of the origin for the division as 1⁄60 part of the hour (and the second 1⁄60 of the minute) have ever been found, despite many speculations.

Source: Wikipedia Topic: minute

Hour

An hour (symbol: h; also abbreviated hr.) is a unit of time conventionally reckoned as 1⁄24 of a day and scientifically reckoned as 3,599–3,601 seconds, depending on conditions. The seasonal, temporal, or unequal hour was established in the ancient Near East as 1⁄12 of the night or daytime. Such hours varied by season, latitude, and weather. It was subsequently divided into 60 minutes, each of 60 seconds. Its East Asian equivalent was the shi, which was 1⁄12 of the apparent solar day; a similar system was eventually developed in Europe which measured its equal or equinoctial hour as 1⁄24 of such days measured from noon to noon. The minor variations of this unit were eventually smoothed by making it 1⁄24 of the mean solar day, based on the measure of the sun's transit along the celestial equator rather than along the ecliptic. This was finally abandoned due to the minor slowing caused by the Earth's tidal deceleration by the Moon. In the modern metric system, hours are an accepted unit of time equal to 3,600 seconds but an hour of Coordinated Universal Time (UTC) may incorporate a positive or negative leap second, making it last 3,599 or 3,601 seconds, in order to keep it within 0.9 seconds of universal time, which is based on measurements of the mean solar day at 0° longitude.

Source: Wikipedia Topic: hour