I have loads of books and recipes from websites which call for US cups, Australian cups and olde English pounds and ounces, but I prefer to work in grams. This is my conversion chart.
Plain flour: 1 cup = 150g / 1/2 cup = 75g / 1/4 cup = 35g
Cocoa: 1 cup = 100g / 1/2 cup = 50g / 1/4 cup = 25g
Caster sugar: 1 cup = 200g / 1/2 cup = 100g / 1/4 cup = 50g
Soft brown sugar: 2/3 cup = 115g
Rolled oats: 1 cup = 90g
Desiccated coconut: 1 cup = 120g
Buttermilk: 1 cup = 250g / 1/2 cup = 125g
Oil: 1 cup = 200g / 1/2 cup = 100g / 1/4 cup = 50g
Butter: 1 stick / 1/2 cup = 100g
Water: 1 cup = 250ml / 1/2 cup = 125ml / 1/4 cup = 60ml