Among common milks you’ll find at a grocery store, ultra-filtered cow’s milk has the highest protein at about 13 grams per 8-ounce glass. Standard cow’s milk comes in next at 8 grams per cup, and soy milk matches it closely at 7 to 8 grams. If you look beyond typical dairy, sheep’s milk and buffalo milk actually beat regular cow’s milk in protein concentration.
How Different Milks Compare, Cup for Cup
The protein gap between milk types is enormous. Here’s how they stack up per 8-ounce (240 ml) serving:
- Ultra-filtered cow’s milk: 13 g
- Cow’s milk (skim or 1%): 8 g
- Soy milk: 7–8 g
- Pea protein milk: 7–8 g
- Oat milk: 2–4 g
- Almond milk: 1 g
- Coconut milk (beverage): 0–1 g
- Rice milk: 0–1 g
That’s not a typo on almond milk. A full glass gives you roughly one gram of protein, which is essentially negligible if you’re counting on it as a protein source. Oat milk fares only slightly better. The popular nut and grain milks are mostly water, oil, and starch with very little of the original plant protein making it into the final product.
Ultra-Filtered Milk: The Highest-Protein Option
Ultra-filtered milk starts as regular cow’s milk and gets pushed through fine membranes that concentrate the protein while removing some of the lactose and sugar. The result is roughly 50% more protein than standard milk, landing at about 13 grams per cup. Brands like Fairlife and Good Karma use this process. Because the filtration also strips out much of the lactose, many people who are mildly lactose intolerant can drink it without issues.
If you’re looking for maximum protein in a glass of milk without adding powder or supplements, ultra-filtered milk is the clear winner on store shelves.
Sheep and Buffalo Milk Beat Regular Cow’s Milk
Standard cow’s milk contains about 3.5% protein by weight. That’s respectable, but sheep’s milk comes in at roughly 4.4% and buffalo milk at about 4.2%. Per cup, that translates to an extra 2 to 3 grams compared to regular cow’s milk. Goat milk, despite its reputation as a high-end alternative, is actually similar to cow’s milk at around 3.4% protein.
Sheep and buffalo milk are harder to find in liquid form in most countries, but they’re commonly consumed in parts of the Mediterranean, South Asia, and the Middle East. You’re more likely to encounter them as cheese (pecorino, mozzarella di bufala) or yogurt than as a carton of drinking milk. If you do find them, they’re noticeably thicker and richer than cow’s milk because they’re higher in both protein and fat.
Soy and Pea Milk Are the Only Plant Options Worth Counting
Among plant-based milks, soy and pea protein varieties are the only two that consistently deliver around 8 grams of protein per serving. That’s enough to meet the U.S. school nutrition program standards, which require non-dairy beverages to provide at least 8 grams of protein per serving. No other plant milk qualifies.
Both soy and pea protein also have complete amino acid profiles, meaning they supply all nine essential amino acids your body can’t make on its own. That matters because protein quantity alone doesn’t tell the whole story.
Protein Quality Varies as Much as Quantity
A scoring system called DIAAS measures how well your body can actually digest and use the protein in a food. A score of 1.0 or higher means the protein is highly digestible and complete. Soy milk scores about 1.08, which is excellent and comparable to dairy. The drop-off from there is steep: coconut-based beverages score 0.72, oat milk 0.59, rice milk 0.43, and almond milk just 0.39.
In practical terms, the single gram of protein in almond milk is also lower-quality protein that your body uses less efficiently. So the effective protein you get from a cup of almond milk is even less than that one gram suggests. Cow’s milk protein, which is about 80% casein and 20% whey, scores at the top of the digestibility scale. Casein digests slowly and provides a sustained release of amino acids, while whey digests quickly, which is why it’s popular in post-workout supplements.
Fortified Plant Milks Are Closing the Gap
Manufacturers are increasingly adding protein isolates from peas, chickpeas, and lentils to plant milks that would otherwise be protein-poor. Some brands now blend multiple plant proteins to create a more complete amino acid profile. Califia Farms, for example, has introduced lines using pea and chickpea protein blends specifically to compete with dairy on protein content.
If you’re shopping for a high-protein plant milk, check the nutrition label rather than trusting the base ingredient. An “oat milk” fortified with pea protein isolate might deliver 7 or 8 grams per serving, while a plain oat milk from a different brand delivers 3. The variation between brands within the same category can be as large as the variation between categories.
Quick Guide to Picking the Highest-Protein Milk for You
If your only goal is maximum protein per cup and you drink dairy, ultra-filtered milk at 13 grams is the straightforward choice. Regular cow’s milk at 8 grams is still a strong option and costs less. For plant-based drinkers, soy milk and pea protein milk are the only reliable options that match dairy’s protein content and amino acid quality. Everything else, including almond, oat, coconut, and rice milk, falls well short unless it’s been specifically fortified with added protein isolates.
For anyone using milk as an ingredient in smoothies, oatmeal, or cooking rather than drinking it straight, adding a tablespoon or two of nonfat dry milk powder to any milk is an easy hack. Milk protein concentrate powders can contain up to 85% protein by weight, and they dissolve reasonably well in liquid. It’s a practical way to boost protein without switching to a milk you don’t enjoy.