81 US customary cups in imperial gallons

Conversion formula
How to convert 81 US customary cups to imperial gallons?

We know (by definition) that: $1\mathrm{uscup}\approx 0.0520421365393118\mathrm{imperialgallon}$

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

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

Conclusion: 81 ⁢ uscup ≈ 4.215413059684256 ⁢ imperialgallon

Conversion in the opposite direction

The inverse of the conversion factor is that 1 imperial gallon is equal to 0.237224676642934 times 81 US customary cups.

It can also be expressed as: 81 US customary cups is equal to $\frac{1}{\mathrm{0.237224676642934}}$ imperial gallons.

Approximation

An approximate numerical result would be: eighty-one US customary cups is about four point two one imperial gallons, or alternatively, a imperial gallon is about zero point two four times eighty-one US customary cups.