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Oat milk vs soy milk

By our estimate, soy milk is more filling per calorie than oat milk: 4 versus 2 out of 5. Soy milk has fewer calories: 33 kcal per 100 ml, versus 45 for oat milk, so the same calories come with more grams of food.

Two plant-based milks.

Prepared by
Last updated
Sources
2 primary
Data
USDA FDC 2705412 and 175215

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Key differences

  • Soy milk provides more protein per calorie: 8.7 g per 100 kcal, versus 1.5 g for oat milk.
  • Soy milk has fewer calories: 33 kcal per 100 ml, versus 45 for oat milk, so the same calories come with more grams of food.
  • Neither provides a meaningful amount of fiber: 0.5 and 0.5 g per 100 g.

Comparison per 100 g and per serving

Values per 100 g or 100 ml (1 ml is treated as about 1 g) and per typical serving. USDA descriptions: Oat milk; Soy milk, unsweetened, calcium-fortified.
NutrientOat milkserving: 250 ml (8.5 fl oz)Soy milkserving: 250 ml (8.5 fl oz)Difference
Calories45 kcal per 100 ml (3.4 fl oz)113 kcal per serving33 kcal per 100 ml (3.4 fl oz)83 kcal per serving−12 kcal per 100 ml (3.4 fl oz)−30 kcal per serving
Protein0.7 g per 100 ml (3.4 fl oz)1.7 g per serving2.9 g per 100 ml (3.4 fl oz)7.2 g per serving+2.2 g per 100 ml (3.4 fl oz)+5.5 g per serving
Carbohydrates5.4 g per 100 ml (3.4 fl oz)13.4 g per serving1.7 g per 100 ml (3.4 fl oz)4.4 g per serving−3.6 g per 100 ml (3.4 fl oz)−9.1 g per serving
of which sugars2 g per 100 ml (3.4 fl oz)5.1 g per serving0.4 g per 100 ml (3.4 fl oz)1 g per serving−1.6 g per 100 ml (3.4 fl oz)−4.1 g per serving
Fiber0.5 g per 100 ml (3.4 fl oz)1.3 g per serving0.5 g per 100 ml (3.4 fl oz)1.3 g per serving0 g per 100 ml (3.4 fl oz)0 g per serving
Fat2.3 g per 100 ml (3.4 fl oz)5.8 g per serving1.6 g per 100 ml (3.4 fl oz)4 g per serving−0.7 g per 100 ml (3.4 fl oz)−1.8 g per serving
of which saturated0.2 g per 100 ml (3.4 fl oz)0.5 g per serving0.2 g per 100 ml (3.4 fl oz)0.5 g per serving0 g per 100 ml (3.4 fl oz)0 g per serving
Water91.3 g per 100 ml (3.4 fl oz)228.3 g per serving93.1 g per 100 ml (3.4 fl oz)232.8 g per serving+1.8 g per 100 ml (3.4 fl oz)+4.4 g per serving
Protein per 100 kcal1.5 g8.7 g+7.2 g
Estimated satiety (1 to 5)2 / 54 / 5+2

In bold, the value more favorable to satiety when the gap is clear. Difference: Soy milk minus Oat milk. Source: USDA FDC 2705412 and 175215.

Per typical serving

With typical servings, 250 ml (8.5 fl oz) of oat milk has about 113 kcal and 1.7 g of protein, and 250 ml (8.5 fl oz) of soy milk about 83 kcal and 7.2 g.

The typical serving is a common amount used for the math, not a recommendation. Ounces are rounded US equivalents; the values come from the database entries cited in the sources.

Which is more filling?

By our estimate, soy milk is more filling per calorie than oat milk: 4 versus 2 out of 5.

  • Oat milk: Calculation: 1 (base) + 2 (very low energy density: 45 kcal/100 g) + 0 (protein: 1.5 g/100 kcal) + 0 (fiber: 1.1 g/100 kcal) − 1 (liquid, less filling than a solid; 2.0 g of sugars, under 8) = 2.
  • Soy milk: Calculation: 1 (base) + 2 (very low energy density: 33 kcal/100 g) + 2 (protein: 8.7 g/100 kcal) + 0 (fiber: 1.5 g/100 kcal) − 1 (liquid, less filling than a solid; 0.4 g of sugars, under 8) = 4.

The 1 to 5 score is our own estimate: it starts at 1 point, adds points for low energy density, for protein and fiber per 100 kcal, and for the water in solid foods, and subtracts points for drinks with calories. It is useful for comparing foods with each other; it is not a measurement in people.

When to choose each one

Oat milk

On the numbers it does not stand out from soy milk in protein, calories, or fiber, so taste, price, or habit can decide.

Soy milk

  • If you want more protein per calorie: 8.7 g per 100 kcal.
  • If you want to eat more grams for the same calories: 33 kcal per 100 ml.
  • If you want more protein in a typical serving: 7.2 g in 250 ml (8.5 fl oz).
  • If you prefer a lighter typical serving: about 83 kcal in 250 ml (8.5 fl oz).

On a GLP-1 medication

Oat milk. “Low energy density”: plenty of volume for few calories; make sure it does not push protein foods off your plate. “Hydrating”: a lot of water, which contributes to hydration when you eat and drink less.

Soy milk. “Low energy density”: plenty of volume for few calories; make sure it does not push protein foods off your plate. “Hydrating”: a lot of water, which contributes to hydration when you eat and drink less.

These are general guidelines, not medical advice: everyone tolerates foods differently.

Full food pages

  • Oat milk: every nutrient, frequently asked questions, and similar foods.
  • Soy milk: every nutrient, frequently asked questions, and similar foods.

Other comparisons

See all comparisons

Sources

Sources for the data on this page, with the access date.

  1. U.S. Department of Agriculture, Agricultural Research Service.USDA FoodData Central (FNDDS 2021-2023): Oat milk (FDC ID 2705412).accessed .
  2. U.S. Department of Agriculture, Agricultural Research Service.USDA FoodData Central: Soymilk (all flavors), unsweetened, with added calcium, vitamins A and D (FDC ID 175215).accessed .