Soy milk and pea milk top the list, each delivering 7 to 8 grams of protein per cup. That puts them nearly on par with cow’s milk, which contains about 8 grams per cup. Most other plant-based milks fall well short of that mark, so your choice matters if protein is a priority.
Soy Milk: The Original High-Protein Option
Unsweetened soy milk provides around 7 grams of protein per cup (240 ml). It’s been the go-to dairy alternative for decades, and for good reason: soy is one of the few plant proteins considered “complete,” meaning it contains all nine essential amino acids your body can’t make on its own. That completeness matters because not all protein is equally useful to your muscles and tissues.
Soy milk is also the most widely available high-protein plant milk. Nearly every grocery store carries multiple brands, and it’s the default substitute at most coffee shops. If you’re replacing cow’s milk in cereal, smoothies, or cooking, soy is the closest nutritional match across the board.
Pea Milk: The Newer Contender
Pea milk, made from yellow split peas, matches or slightly edges out soy with about 8 grams of protein per cup in most unsweetened versions. Flavored varieties like vanilla and chocolate typically hold at 8 grams as well. Brands like Ripple popularized this category starting around 2016, and it’s grown quickly since.
Pea protein is also close to complete in its amino acid profile, though it’s slightly lower in one amino acid (methionine) compared to soy. For most people eating a varied diet, this difference is negligible. Pea milk has a creamier, thicker texture than soy, which some people prefer in coffee or cereal. It’s also free of the most common allergens: dairy, soy, tree nuts, and gluten.
How Other Plant Milks Compare
The gap between the top two and everything else is significant. Here’s what you get per cup from the most popular alternatives:
- Oat milk: 3 grams of protein. Popular for its creamy texture and mild flavor, but it’s primarily a carbohydrate source with 14 grams of carbs per cup.
- Hemp milk: 3 grams of protein. Hemp seeds are technically a complete protein with all essential amino acids, but the milk is too diluted to deliver meaningful amounts.
- Almond milk: 1 gram of protein. Almonds themselves are protein-rich, but standard almond milk is mostly water, typically made from just a small percentage of actual almonds.
- Cashew milk: Less than 1 gram of protein. Similar to almond milk, it’s extremely diluted and offers almost no protein.
If you drink two cups of almond milk a day thinking you’re getting meaningful protein, you’re taking in just 2 grams total. The same amount of soy or pea milk would give you 14 to 16 grams.
Fortified High-Protein Versions
Some brands now sell plant milks specifically designed to compete with protein shakes. Silk Ultra, a soy-based product with added protein, packs 20 grams per cup. Good Karma makes a protein-fortified flax milk with about 5 grams per serving (less than the 8 grams on the front of the package suggests, so check the nutrition label carefully).
These fortified options blend a base milk with concentrated plant protein isolates, usually from soy or pea. They’re useful if you’re trying to hit a higher daily protein target without adding extra foods, but they tend to cost more and may have a slightly chalky texture compared to standard versions.
Protein Quality, Not Just Quantity
Grams per cup only tells part of the story. How well your body can actually use that protein varies between sources. Researchers measure this with a digestibility score that accounts for amino acid completeness and how efficiently your gut absorbs the protein. Cow’s milk scores a perfect 1.0 on this scale. Almond milk scores just 0.4, meaning your body extracts less usable protein from each gram.
Soy protein scores close to 1.0 in most studies, making it the highest-quality plant milk protein by this measure. Pea protein scores slightly lower but still well above nuts and grains. This is another reason soy and pea milk stand apart from the pack: not only do they have more protein per cup, but a higher percentage of that protein actually gets put to work in your body.
What the USDA Considers a Real Milk Substitute
The USDA sets specific standards for plant milks served in school lunch programs and other federal nutrition programs. To qualify as a fluid milk substitute, a nondairy beverage must provide at least 8 grams of protein per cup, along with minimum levels of calcium, vitamin D, and several other nutrients. By that benchmark, only pea milk consistently meets the protein threshold in its standard form. Most soy milks come in at 7 grams, just under the cutoff, though some brands hit 8.
Oat, almond, cashew, rice, and coconut milks all fall far below this standard. If you’re relying on plant milk as a primary protein source for yourself or your kids, this is worth keeping in mind. Two or three daily servings of a low-protein plant milk could leave a real gap in your intake compared to what dairy would provide.
Choosing Based on Your Goals
If protein is your main concern, soy and pea milk are your only strong options in the standard (non-fortified) category. Between the two, pea milk has a slight edge in grams, while soy has a longer track record and better-studied protein quality. Both work well as straightforward swaps for cow’s milk in most recipes and meals.
If you prefer oat or almond milk for taste reasons, that’s fine, but treat them as flavored beverages rather than protein sources. You’ll need to make up the difference elsewhere: a handful of nuts, a serving of beans, or a scoop of protein powder in your smoothie can easily close the gap. One cup of soy milk in your morning cereal and one in a smoothie gives you about 14 grams of protein before you’ve even thought about solid food.