You may have seen both light and dark soy sauces on your supermarket shelves, but do you know the difference between them and, most importantly, which one you should be using?07:18, 22 Jun 2026Soy sauce is a condiment made from soybeans, wheat, water, and salt, produced through fermentation that can last months to years. This process generates a distinctive, complex flavour that harmonises saltiness, sweetness, and bitterness.‌It's an excellent method for enhancing the taste of salmon fillets, baked beans, and, traditionally, stir-fry dishes.‌Glass bottles of light and dark soy sauces stand alongside each other on supermarket shelves, appearing virtually identical and yet generating considerable confusion about which works best.‌Light soy versus dark soy – surely one is merely a more concentrated version of the other? That's not entirely accurate. There is a substantial difference between them.What is light soy sauce?If a recipe calls for "soy sauce", it nearly always refers to light soy. This variety of soy is thin, salty and aromatic.‌It's the standard soy that is employed for seasoning, marinades and dipping sauces, particularly in Chinese cuisine.A little goes a long way, as this soy is fermented for flavour rather than colour, so you only need a modest amount to introduce savoury depth without darkening your food excessively.Light soy sauce is all about seasoning and balance – it contributes salt, savouriness and aroma without dominating a dish. These are the occasions it truly excels.‌What is dark soy sauce?Dark soy is thicker, deeper in colour and marginally sweeter than light soy. This is due to its longer ageing process and the frequent addition of molasses or caramel.It's the secret behind that glossy, mahogany restaurant-quality finish on dishes such as braised pork, fried noodles, or stir-fried beef.While light soy is primarily concerned with flavour, dark soy is less about seasoning and more about delivering colour and depth — and this distinction dictates how each is used in the kitchen.Article continues belowDo you need both light and dark soy sauce in your fridge?If you regularly prepare Asian dishes, then both bottles absolutely warrant a place in your fridge, as they fulfil entirely different purposes and cannot be substituted for one another. Light soy is for seasoning, while dark soy is for imparting colour.However, if you only occasionally dabble in Asian cooking and want to preserve precious space in your pantry or fridge, light soy is the one to reach for every time. Dark soy has its merits, but it's far from essential.