Yeah, but that's not very useful for comparing the size of gallons because the USA uses a different fluid oz than the rest of the world.
If you just look at the number of ounces in a gallon (128 vs. 160), you would think that a US gallon is 4/5 the size of a Canadian/Imperial gallon. But the actual ratio is almost exactly 5/6.
I spent many hours in my youth mixing photo chemicals from Kodak with mixing directions in US ounces and gallons using bottles and measuring tools marked in Imperial measure. We just converted everything to metric to simplify the task.
Dave