A liquid butt-load is equivalent to 108 imperial (UK) gallons.
Butt-load is also a measure of weight equalling 2,016 lbs.
One could be forgiven for assuming that a butt-load would be equivalent to a crap-load or a shit-load – basically a lot. In fact, a butt and butt-load are actual, albeit little-used, units of measurement.
Entry 6 of 6
1: a large cask especially for wine, beer, or water
2: any of various units of liquid capacity
especially : a measure equal to 108 imperial gallons (491 liters)
There is also a more archaic definition from Irish, where a butt is a two or three-wheeled cart similar to a wheelbarrow.
In the above definition, you can see it specifically states that a butt-load is “a cart-load, about 18 cwt”. Cwt is an abbreviation for hundredweight and as usual, there is a British imperial unit and an American imperial unit that differ slightly. An American (or “short”) hundredweight is 100lb (45.4kg). A British (or “long”) hundredweight is 8 stone, which is 112 lb (50.8kg).
Since the source of this measure above is from the English dialect, we can assume they meant the 112lb version of cwt. So the weight of a British imperial butt-load would be 2,016 lbs.
How do the two definitions compare?
We have a liquid measurement of 108 imperial gallons and a weight measurement of 2,016 lbs. Which is bigger, or are they the same?
A liter of water weighs 1 kg which means that one imperial (UK) gallon of water weighs about 10 lbs. So, a butt-load containing 108 imperial gallons of liquid is going to weigh roughly 1,080 lbs, a little over half of what a butt-load by weight equals.
If someone asks you to transport a butt-load of something, you’re better off if it’s a liquid butt-load. In this author’s opinion, this is the only time a liquid butt-load is preferable. 🙂
Could butt-load just be a misheard boat-load?
Some sources have suggested that a butt-load is just based on a mishearing of the word boat-load. It seems to me that the existence of actual precise numerical quantities attributed to butt-load would suggest that butt-load isn’t just an accident of language.