Pick the one that feels heavy for its size with thin, fine-textured skin. Weight is juice, and thick bumpy rind means more pith and less of what you came for. Citrus does not ripen after picking, so what you buy is what you get.
What to check
Feelheavy for its size, firm with a slight yield. Hard and light for its size is the bad combination, because that means thick rind and little juice. Weight decides it, not firmness.
Lookthin, smooth skin. Deep wrinkles or dried, hardened patches mean it has been sitting and losing water.
Notea lime turning yellow is a riper, juicier lime. Shoppers will not buy yellow limes, so stores mark them down or throw them away. That markdown bag is the best value in the citrus set, and it exists because of a customer prejudice rather than a quality problem.
Buying for whenlemons peak in winter and early spring, limes in summer. Bagged citrus is sold by count so the bag is usually the smaller fruit, while loose is the larger fruit priced each. For juice by volume the bag often wins.
Common mistakepicking the shiniest fruit. Supermarket citrus is routinely waxed, so shine tells you about the coating, not the fruit. And if the only option is a mesh bag, heft the whole bag and check the bottom for soft or moldy fruit, since you cannot judge them one at a time.
Before you cut it: bring it to room temperature and roll it firmly under your palm. Cold citrus juices poorly, and rolling breaks the juice vesicles. If you end up with a thick-rind lemon anyway, stop fighting it for juice and zest it instead, because the rind on those is the good part.
Written by the team behind RIPE, a free app that reads a photo of the whole produce pile and rings the ripest ones. Every cue above is one you can check with your own hands, and it all works with no app at all.