Unsweetened almond milk has fewer calories than unsweetened oat milk. A one-cup serving (240 mL) of unsweetened almond milk contains about 59 calories, while the same amount of unsweetened oat milk comes in at roughly 79 calories. That’s a 20-calorie difference per cup, which adds up if you’re pouring multiple servings a day into coffee, cereal, or smoothies.
Why Oat Milk Has More Calories
The calorie gap comes down to what each drink is made from. Oats are a starchy grain, and during manufacturing, enzymes break down that starch into simple sugars like maltose and glucose. This process is what gives oat milk its naturally sweet taste, but it also means the final product carries more carbohydrates per cup than almond milk. Almonds, by contrast, are low in carbohydrates and high in fat, but commercial almond milk uses a relatively small amount of actual almonds blended with a lot of water, diluting both the fat and the calories.
Many oat milk brands also add small amounts of oil (rapeseed or sunflower are the most common) to create a creamier mouthfeel that mimics dairy. These added fats nudge the calorie count a bit higher. A typical ingredient list for oat milk reads something like: water, oats (9 to 15%), rapeseed oil, salt, and added vitamins. Almond milk usually skips the added oil entirely.
Sweetened Versions Widen the Gap
The numbers above apply to unsweetened varieties. If you’re buying original or flavored versions, the calorie difference grows. Sweetened oat milk can easily reach 120 calories or more per cup because the added sugar sits on top of the sugars already created during processing. Sweetened almond milk rises too, but it starts from a lower baseline, so it typically stays under 90 calories per cup. Always check the label, since “original” doesn’t mean unsweetened for most brands.
How They Compare on Blood Sugar
Calories aren’t the whole picture if you’re watching your weight or managing blood sugar. Oat milk and almond milk land in a similar range on the glycemic index, with lab estimates for commercial products falling between roughly 49 and 64 for both. That said, oat milk delivers more total carbohydrate per serving, so the actual blood sugar impact after drinking a full cup tends to be greater. The sugars in most plant milks are “free sugars” like glucose, sucrose, and maltose, which the body absorbs quickly compared to the lactose in dairy milk.
If you’re managing diabetes or insulin resistance, the lower carbohydrate load in almond milk makes it the more predictable choice for keeping blood sugar steady.
Where Oat Milk Wins
Oat milk does have one nutritional advantage that matters for day-to-day eating: fiber. It retains some soluble fiber from the oats, which can contribute to feeling full and support digestion. Almond milk is essentially fiber-free. That small amount of fiber in oat milk may explain why some people find it more satisfying in a bowl of cereal or as a mid-morning latte, even though it contains 20 more calories.
Oat milk also tends to have a thicker, creamier texture straight out of the carton, which makes it a popular swap in coffee drinks where almond milk can taste thin or separate when heated. If your main use is steaming milk for lattes, you may prefer oat milk for practical reasons that have nothing to do with calories.
Fortification Matters More Than the Base
Neither oat milk nor almond milk naturally contains meaningful amounts of calcium, vitamin D, or vitamin B12. Those nutrients show up only when manufacturers add them. Most major brands fortify to at least 15% of the daily value per serving for calcium, vitamin D, and B12, putting them roughly in line with dairy milk. But not all brands fortify equally, and store-brand or organic versions sometimes skip fortification altogether.
One thing worth knowing: oats contain compounds called phytates that can bind to calcium, iron, and zinc, reducing how much your body actually absorbs. Even when oat milk is fortified with calcium, some of that calcium may pass through without being used. This doesn’t make oat milk a bad choice, but if calcium intake is a priority, checking for fortified versions and pairing them with other calcium-rich foods is a smart move.
Which One to Choose for Weight Loss
If your sole goal is cutting calories, unsweetened almond milk is the clear winner at 59 calories per cup versus 79. Over the course of a week, someone using two cups a day would save about 280 calories by choosing almond milk. That’s a modest but real difference, roughly equivalent to skipping a small snack each day.
In practice, the best choice depends on what you’re using it for. Almond milk works well in smoothies, overnight oats, and anywhere you want a neutral, low-calorie liquid. Oat milk shines in coffee, baking, and recipes where you want body and a slight sweetness without adding sugar. Picking the one you actually enjoy drinking consistently will do more for your overall diet than optimizing 20 calories per cup.