Sent by CaraEditor: Cara, here are standard measurements for lemon and lime juice:
• 1 lemon yields: 3 tablespoons juice
• 1 lime yields: 2 tablespoons juice
Now, of course there are variations between fruits of different sizes, and there will also be variations depending on what kind of extraction you use. But a good recipe should also specify the actual quantity needed, unless it's a looser recipe for a salad dressing or something like that.
(Image: Faith Durand)