Knowing how much juice you can extract from a lemon is a useful, especially if a recipe gives the measurement in volume instead of whole fruit.
When a recipe calls for the juice of one lemon, it usually won’t make a huge difference if you use a small, medium or large fruit: the best thing to do is to juice it, then add a little lemon juice to the dish, then add a little more to taste.
However, when a baking recipe calls for lemon juice measured in mililitres or cup sizes, you need to be more accurate. The same goes for when you are making jams and jellies where you need to be accurate about the amount of lemon juice you add.
We've squeezed an average sized lemon and measured the quantity of juice it yielded:
One lemon, weighing about 120g, yields approximately 40 mls lemon juice.
Three lemons, each weighing about 120g, yields approximately 120 mls (1/2 cup) lemon juice.
Six lemons – each weighing about 120g – yields approximately 240 mls (1 cup) lemon juice.