21 millimeters in inches

Result

The conversion result is: 21 millimeters is equivalent to 0.826771653543307 inches.[1]

Conversion formula
How to convert 21 millimeters to inches?

We know (by definition) that: 1 mm ≈ 0.039370079 in.

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

1 mm / 21 mm ≈ 0.039370079 in / x in

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

x in ≈ (21 mm / 1 mm) * 0.039370079 in → x in ≈ 0.826771659 in

Conclusion:

21 mm ≈ 0.826771659 in

Conversion in the opposite direction

The inverse of the conversion factor is that 1 inch is equal to 1.20952380952381 times 21 millimeters.

It can also be expressed as: 21 millimeters is equal to 1 / 1.20952380952381 inches.

Approximation

An approximate numerical result would be: twenty-one millimeters is about zero point eight three inches, or alternatively, a inch is about one point two zero times twenty-one millimeters.

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.