815 US dry barrels in imperial gallons
Result
The conversion result is: 815 US dry barrels is equivalent to 20729.0453380729 imperial gallons.[1]
Conversion formula
How to convert 815 US dry barrels to imperial gallons?
We know (by definition) that: 1 drybarrel ≈ 25.4344114577582 imperialgallon.
We can set up a proportion to solve for the number of imperial gallons.
1 drybarrel / 815 drybarrel ≈ 25.4344114577582 imperialgallon / x imperialgallon
Now, we cross multiply to solve for our unknown x:
x imperialgallon ≈ (815 drybarrel / 1 drybarrel) * 25.4344114577582 imperialgallon → x imperialgallon ≈ 20729.04533807293 imperialgallon
Conclusion:
815 drybarrel ≈ 20729.04533807293 imperialgallon

Conversion in the opposite direction
The inverse of the conversion factor is that 1 imperial gallon is equal to 4.82414883894004e-05 times 815 US dry barrels.
It can also be expressed as: 815 US dry barrels is equal to 1 / 4.82414883894004e-05 imperial gallons.
Approximation
An approximate numerical result would be: eight hundred and fifteen US dry barrels is about twenty thousand, seven hundred and twenty-nine point zero four imperial gallons, or alternatively, a imperial gallon is about zero times eight hundred and fifteen US dry barrels.
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.