21 imperial gallons in US gallons

Conversion formula
How to convert 21 imperial gallons to US gallons?

We know (by definition) that: $1\mathrm{imperialgallon}\approx 1.20094992550486\mathrm{usgallon}$

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 ⁢ imperialgallon ≈ 25.219948435602056 ⁢ usgallon

Conversion in the opposite direction

The inverse of the conversion factor is that 1 US gallon is equal to 0.0396511516489995 times 21 imperial gallons.

It can also be expressed as: 21 imperial gallons is equal to $\frac{1}{\mathrm{0.0396511516489995}}$ US gallons.

Approximation

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