When lime juice runs out, lemon juice at 1:1 is the closest substitute — both have pH 2.0–2.4 from citric acid, so lemon juice activates baking soda the same way, prevents browning identically in guacamole, and provides the same acid-denaturing action in ceviche. The flavor shift is from lime's limonene-dominant aroma to lemon's linalool-forward note — functionally identical in cooked dishes and marinades but noticeable in cocktails where lime character is the point. For a non-citrus backup in dressings, white wine vinegar at half the amount adds clean acidity without sweetness.
Substitutes
Lemon Juice — 1:1. Best substitute. Less floral than lime but same acidity. Works in guacamole, margaritas, and Thai recipes.
White Wine Vinegar — 1/2 tsp vinegar per 1 tsp lime juice. Provides acidity without citrus character. Best in cooking and marinades. Not for cocktails or guacamole.
Rice Vinegar — 1:1. Milder and slightly sweet. Works well as a lime substitute in Asian dishes and light salad dressings.
Calamansi Juice — 1:1. Excellent Southeast Asian substitute. Similar tartness with a floral, slightly sweeter note. Best in Filipino, Thai, and Malaysian recipes. Not ideal for cocktails where lime's distinct character matters.
Yuzu Juice — 3/4 tsp yuzu juice per 1 tsp lime juice. Japanese citrus with distinct floral, bergamot-like aroma. More fragrant and complex than lime. Excellent in Asian-style dressings, ponzu sauces, and cocktails. Use slightly less as yuzu is more aromatic.