How much protein is in milk?
Cow's milk contains about 3.3 to 3.5 g of protein per 100 ml. That is roughly 8 to 9 g in 250 ml, 17 g in 500 ml and 33 to 35 g in one litre. Fat percentage changes calories more than protein.
Key takeaways
- Cow's milk contains about 3.3 to 3.5 g protein per 100 ml.
- A 250 ml glass provides roughly 8 to 9 g of protein.
- Skimmed, semi-skimmed and whole milk have similar protein but different calories.
- Milk protein is mostly casein, with a smaller whey fraction.
- Plant drinks vary widely, so their labels are more useful than a generic estimate.
Cow's milk contains about 3.3 to 3.5 g of protein per 100 ml. The arithmetic is simple, but glass sizes and plant-based alternatives make the everyday answer less obvious.
Protein in milk by volume
- 3.4 gCow's milk100 ml
- 6.8 gSmall glass200 ml
- 8.5 gLarge glass250 ml
- 17 gHalf litre500 ml
- 34 gOne litre1,000 ml
For tracking, 3.4 g per 100 ml is a useful default. Use the carton when it differs, especially for filtered or fortified products.
Protein in 250 ml, 500 ml and one litre
| Amount of cow's milk | Approximate protein |
|---|---|
| 100 ml | 3.4 g |
| 200 ml | 6.8 g |
| 250 ml | 8.5 g |
| 500 ml | 17 g |
| 1 litre | 34 g |
A splash in coffee contributes little. A large latte or bowl of cereal can contribute a meaningful amount because the volume is larger.
Whole, semi-skimmed and skimmed milk
Removing milk fat changes calories much more than protein. Most plain cow's milks remain near 3.3 to 3.5 g protein per 100 ml across fat levels. Filtered high-protein milk is different, so use its label.
What types of protein are in milk?
Milk protein is roughly 80 percent casein and 20 percent whey. Casein forms curds and digests more slowly, while whey remains in the liquid portion. Both are complete proteins containing all nine essential amino acids.
This is why strained dairy foods can be especially protein dense. Removing liquid concentrates the solids in Greek yoghurt, while curd formation produces cottage cheese.
What about plant-based milk?
Plant drinks are not nutritionally interchangeable. Soy milk is often closest to cow's milk for protein. Pea-based products can also be high. Almond, oat, rice and coconut drinks are frequently much lower unless protein has been added.
Recipes and brands vary too much for one reliable number, so check the carton. Compare protein per 100 ml, not only per serving, because serving sizes differ.
The number to log
Use 3.4 g per 100 ml for ordinary cow's milk when no label is available. That becomes 8.5 g for 250 ml, 17 g for 500 ml and 34 g for one litre.
More questions about Protein in food
How much protein is in one glass of milk?
A 250 ml glass of cow's milk provides about 8 to 9 g of protein. A smaller 200 ml glass provides roughly 7 g.
Which type of cow's milk has the most protein?
Whole, reduced-fat and skimmed milk are usually close, at about 3.3 to 3.5 g per 100 ml. Brand differences can be larger than the difference between fat levels.
What types of protein are in milk?
Cow's milk protein is roughly four-fifths casein and one-fifth whey. Both contain all nine essential amino acids.
