Heavier, not bigger, lemons make more juice

While it may seem obvious that the larger a lemon is, the more juice it will produce, this is actually not true. When picking your lemons, you need to pick them based on their weight and not on their appearance. Lemons grow to a certain size and then continually produce more and more lemon juice within them. So a smaller lemon which has matured longer may actually produce more juice than a lemon which is larger but has not matured for as long.