How much protein is in soy milk?

The one plant milk that actually has protein

Walk the plant-milk shelf and almost everything on it is protein-water. Unsweetened almond milk has about 1 gram of protein per cup; oat, rice, and coconut milks are in the same near-empty range. Soy milk is the exception, and it’s not a small one. At 3.3 g of protein per 100 g — roughly 8 g in a standard 1 cup (243 g) — soy milk lands within a gram or two of dairy. That single fact is the whole reason to choose it over the other cartons: if you want a plant milk that pulls real nutritional weight rather than just turning your coffee beige, soy is the one that does it.

What makes the number count is quality, not just quantity. Soy is the rare plant food that delivers all nine essential amino acids in usable amounts, so soy milk is a complete protein on its own — no rice-and-beans pairing required. Most plant proteins come with an asterisk; soy doesn’t. That’s why soy milk shows up here as a legitimate protein source instead of a “plant milk, with caveats” footnote, and why it’s the default swap recommended for anyone going dairy-free who doesn’t want to give up the protein at breakfast.

Honest framing: it’s a base, not a shake

The catch is one of scale, and it’s worth being straight about. Eight grams a cup is excellent for a beverage you pour — but it’s still a beverage. Soy milk is something you build onto, not a protein shake that carries a goal by itself. Three cups across a day get you to roughly 24 g; useful, but the real wins come from using it as the liquid in a smoothie, the splash in your oats, or the milk in a latte, where it quietly lifts the protein of everything else.

The other thing to watch is sugar. The protein number doesn’t change between versions, but the sugar does. Flavored and sweetened “original” soy milks add several grams of cane sugar per cup for taste; unsweetened is the clean pick — same ~8 g of complete protein, far less added sugar. One more label note: this USDA reference is the unfortified product, but most soy milks on shelves are fortified with calcium and vitamins D and B12 to mirror dairy. If you’re using soy milk as a true one-for-one replacement for cow’s milk, that fortification line is the part worth checking.

Who it’s for

Soy milk is the dairy-free, vegan-friendly way to keep milk-like protein in your day without the asterisks that hang over every other plant milk. If you’ve cut dairy and noticed your breakfast protein quietly collapsed, this is the fix — it’s the carton that behaves like milk on the macro sheet, not just on the cereal. Where those ~8 g per cup fit into your total depends on your size and goals; our protein-per-day guide walks through the math. And because the spread between brands — sweetened versus unsweetened, fortified versus not — is exactly what separates a clean pick from a sugary one, the specific carton matters. The packaged soy milks below are the options worth reaching for when protein and a short ingredient list are the point.