I make slighty larger portions than would a BIR, starting with 450ml of base, although it does get reduced by boiling-off in cooking (difficult to say by how much - I just keep going untill the texture and oiliness looks right). This is enough for me and the misses. In a madras, for example, I would use 3 large old-fashioned table-spoons full, which proabably equates to 4 x 15ml level tbs measures.