21 feet in inches

Conversion

21 feet is equivalent to 252 inches.^[1]

Conversion formula
How to convert 21 feet to inches?

We know (by definition) that: $1 ft = 12 in$

We can set up a proportion to solve for the number of inches.

\frac{1 ft}{21 ft} = \frac{12 in}{x in}

Now, we cross multiply to solve for our unknown $x$ :

x in = \frac{21 ft}{1 ft} * 12 in \to x in = 252 in

Conclusion: $21 ft = 252 in$

Conversion in the opposite direction

The inverse of the conversion factor is that 1 inch is equal to 0.00396825396825397 times 21 feet.

It can also be expressed as: 21 feet is equal to $\frac{1}{0.00396825396825397}$ inches.

Approximation

An approximate numerical result would be: twenty-one feet is about two hundred and fifty-two inches, or alternatively, a inch is about zero times twenty-one feet.

Units involved

This is how the units in this conversion are defined:

Feet

The foot is a unit of length in the imperial and US customary systems of measurement. Since 1959, both units have been defined by international agreement as equivalent to 0.3048 meters exactly. In both systems, the foot comprises 12 inches and three feet compose a yard.

Wikipedia page of feet

Inches

The inch (abbreviation: in or ″) is a unit of length in the imperial and United States customary systems of measurement now formally equal to 1⁄36 yard but usually understood as 1⁄12 of a foot. Derived from the Roman uncia (twelfth), inch is also sometimes used to translate related units in other measurement systems, usually understood as deriving from the width of the human thumb. Traditional standards for the exact length of an inch have varied in the past, but since the adoption of the international yard during the 1950s and 1960s it has been based on the metric system and defined as exactly 2.54 cm.

Wikipedia page of inches

Footnotes

[1] The precision is 15 significant digits (fourteen digits to the right of the decimal point).

Results may contain small errors due to the use of floating point arithmetic.

Conversion

Conversion formula How to convert 21 feet to inches?

Conversion in the opposite direction

Approximation

Conversion formula
How to convert 21 feet to inches?