As chewie says 2 litres of 100% juice to a Demijohn (DJ) with 800g of sugar will do the trick, if you add more juice you need to subtract the amount of sugar in the carton from the 800g, if you get a 23 litre fermenting vessels multiply the 4.5 litre recipe by 5 for 22.5 litre, you can get away with only using 3 teaspoons of yeast but use 5 teaspoons of all the other ingredients.