Just to put my money where my mouth is, here is a wee bit over 4 gallons of cider turned into cider syrup.
I must say it came out fantastic.
So with 16 quarts to the gallon, on average you will get 2 quarts out of it.
This will depend on the sugar content.
I did not adulterate it with any added sugar it is all natural.
But a person could if they wanted to.
