I don't know about Sweden but here in Germany it's on the price labels that are attached to the shelves.
You have a price per unit. Say a 0.5l bottle of beer costs 0.78 EUR and then you have the price per 100ml or 1l below it (1l = 1.56 EUR). It's marginally useful if you compare the price of rice to the price of Coca Cola but it's really useful if you want to know what's cheaper: Buying a package of 6 1.5l bottles of Coke or buying a crate with 18 0.33l bottles.
We do this in the US. However, not being standardized on the metric system, it can end up being pretty useless. It's usually good, but every so often you come across something like:
Item A: $3, $6/pound
Item B: $4, $0.30/oz
Which defeats the whole purpose of the per-unit price. Occasionally drives me bonkers.
You have a price per unit. Say a 0.5l bottle of beer costs 0.78 EUR and then you have the price per 100ml or 1l below it (1l = 1.56 EUR). It's marginally useful if you compare the price of rice to the price of Coca Cola but it's really useful if you want to know what's cheaper: Buying a package of 6 1.5l bottles of Coke or buying a crate with 18 0.33l bottles.
I'm a sucker for saving pennies ;)