21 US gallons in imperial gallons

Result

The conversion result is: 21 US gallons is equivalent to 17.4861578772088 imperial gallons.[1]

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

We know (by definition) that: 1 usgallon ≈ 0.832674184628989 imperialgallon.

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

1 usgallon / 21 usgallon ≈ 0.832674184628989 imperialgallon / x imperialgallon

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

x imperialgallon ≈ (21 usgallon / 1 usgallon) * 0.832674184628989 imperialgallon → x imperialgallon ≈ 17.48615787720877 imperialgallon

Conclusion:

21 usgallon ≈ 17.48615787720877 imperialgallon

Conversion in the opposite direction

The inverse of the conversion factor is that 1 imperial gallon is equal to 0.0571880916907074 times 21 US gallons.

It can also be expressed as: 21 US gallons is equal to 1 / 0.0571880916907074 imperial gallons.

Approximation

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

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.