21 US customary cups in US gallons

Conversion formula
How to convert 21 US customary cups to US gallons?

We know (by definition) that: $1\mathrm{uscup}\approx 0.0625\mathrm{usgallon}$

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

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

Conclusion: 21 ⁢ uscup ≈ 1.3125 ⁢ usgallon

Conversion in the opposite direction

The inverse of the conversion factor is that 1 US gallon is equal to 0.761904761904762 times 21 US customary cups.

It can also be expressed as: 21 US customary cups is equal to $\frac{1}{\mathrm{0.761904761904762}}$ US gallons.

Approximation

An approximate numerical result would be: twenty-one US customary cups is about one point three one US gallons, or alternatively, a US gallon is about zero point seven six times twenty-one US customary cups.