Oat Milk vs Soy Milk: Nutrition Compared

Oat milk and soy milk are both popular dairy alternatives but they occupy very different nutritional positions. Oat milk is higher in carbohydrates and has a creamy flavour ideal for coffee, while soy milk is significantly higher in protein and more closely mirrors dairy milk's nutritional profile. Understanding the difference helps you pick the right one for your goals.

This is part of our Milk Alternatives Complete Guide. See also Oat Milk vs Almond Milk and Soy Milk vs Whole Milk.

Calories: Similar, Oat Milk Slightly Higher

Oat milk contains approximately 120 calories per cup, while soy milk contains around 80 calories per cup unsweetened. The 40-calorie gap is smaller than the difference between oat milk and almond milk, but still worth noting if you are tracking calories carefully. Over a week of daily use, choosing soy milk over oat milk saves around 280 calories.

Protein: Soy Milk Wins Decisively

This is the most important nutritional difference between the two. Soy milk provides approximately 7g of protein per cup — more than double oat milk's 3g. Soy milk is the only plant-based milk that provides complete protein with all essential amino acids in meaningful amounts, making it the closest plant-based equivalent to dairy milk on this metric. If protein intake is a priority, soy milk is the clear winner.

Carbohydrates: Oat Milk Is Much Higher

Oat milk contains around 16g of carbohydrates per cup compared to soy milk's 4g. For people managing blood sugar, following a low-carb diet, or monitoring their carbohydrate intake, soy milk is the better choice. The starchy carbohydrates in oat milk can cause a more significant blood sugar response than soy milk's lower-carb profile.

Fat: Similar Amounts, Different Types

Both contain around 4–5g of fat per cup. Oat milk's fat is primarily from added oils (often rapeseed or sunflower), while soy milk's fat comes naturally from soybeans and includes a beneficial ratio of unsaturated fats including some omega-3s.

Taste and Versatility

Oat milk performs better in coffee due to its creamier texture and natural sweetness. Soy milk has a slightly beany flavour that some people find noticeable in neutral applications like cereal or plain drinks, though barista soy milk varieties have improved significantly. In cooking and baking, soy milk's higher protein content gives it more body and it performs better in savoury dishes.

Which Should You Choose?

Choose soy milk if: protein content is important, you are replacing dairy milk nutritionally, or you follow a low-carb diet.

Choose oat milk if: you primarily use milk in coffee, prefer a creamier texture, or are not concerned about the higher carb content.

Use our Daily Calorie Needs Calculator to set your daily targets.