Calories in Oatmeal: 166 per Cooked Cup, 153 per Half Cup Dry

Half a cup of dry rolled oats is about 153 calories with 5.3g of protein and 4g of fiber, and a cup cooked with water is about 166 calories, by USDA FoodData Central figures. A cup of dry oats is 307, so "a cup of oatmeal" is one of the most mislogged entries in tracking. Toppings routinely cost more than the oats did.

Official USDA numbers

Dry rolled oats, regular and quick, unfortified (379 calories per 100g):

Portion	Weight	Calories	Protein	Fiber
1/3 cup	27g	102	3.6g	2.7g
40g label serving	40g	152	5.3g	4.0g
1/2 cup	40.5g	153	5.3g	4.1g
1 cup	81g	307	10.7g	8.2g

Cooked with water, no salt (71 calories per 100g):

Portion	Weight	Calories	Protein	Fiber
3/4 cup cooked	175g	124	4.4g	3.0g
1 cup cooked	234g	166	5.9g	4.0g

Instant, fortified, plain, dry: one packet is 28g, which is 101 calories with 3.3g protein. Instant packets are smaller than most people assume, which is the honest reason two packets is the normal habit.

The pattern worth internalizing: oats are about 3.8 calories per dry gram and about 0.7 calories per cooked gram. Same food, different water.

Why the dry and cooked numbers disagree

Nothing is added and nothing is lost. Cooking oats is hydration: 40g of dry oats absorb water and become roughly 180g to 240g of porridge depending on how loose you like it, and the calories stay exactly where they were. That means the cooked-per-cup figure is not a property of oatmeal, it is a property of your water ratio. Make it thick and a cup carries more calories; make it soupy and the same cup carries fewer.

This is why the dry weight is the only honest anchor. If you measure 1/2 cup of dry oats, you know you ate 153 calories of oats no matter how much water went in. If you measure a cup of the finished bowl, you have measured your own cooking style as much as your breakfast. Serious loggers scoop dry and never think about it again.

Cooking in milk is a different matter, because milk is food. A cup of whole milk instead of water adds about 149 calories and shifts the macros substantially, which makes "oatmeal made with milk" a genuinely different entry from "oatmeal," not a rounding difference.

What the toppings actually cost

The oats are the cheap part of the bowl. Using verified numbers from our other staple guides, a standard "healthy" oatmeal assembles like this:

Component	Calories
1/2 cup dry oats	153
1 medium banana, sliced	105
2 tbsp peanut butter	191
Total	449

The peanut butter alone outweighs the oats, at 191 calories for two level tablespoons by USDA's own serving weight. A drizzle of honey is about 64 more per tablespoon, USDA's tablespoon being 21g. This is the whole reason oatmeal has a reputation as both a diet food and a calorie bomb: the base is 153 calories, and the assembled bowl in front of most people is 400 to 600.

Two useful facts if you want the bowl to work harder. Oats carry real fiber, 4g in a half-cup dry serving, which is unusual for a breakfast carb and part of why they hold up until lunch. And oats carry more protein than most grains at 5.3g per serving, though that is still low for a breakfast, which is why a scoop of whey or a side of eggs is the standard fix when you are chasing the protein targets in How to Track Macros.

How I log oatmeal without measuring anything

I stopped measuring oats years ago, which sounds like the opposite of good tracking until you see the trick: my scoop is always the same scoop. The same coffee mug, filled the same way, every morning. I weighed it exactly once, found it was about 45 grams, and now "my usual oats" is a known quantity forever. Consistency does the work that a scale was doing.

What I still have to say out loud is the toppings, because those are the part that changes day to day. In Nouri that means the log is one sentence: "oatmeal with a banana and two spoons of peanut butter." It comes back itemized, oats separate from banana separate from peanut butter, so I can see that the peanut butter was 191 of the 449 and decide whether that is a trade I want tomorrow. When I use a heaped spoon rather than a level one, I say "big spoonful" and the estimate moves. That is the whole system: describe the plate, read the breakdown, correct the one item that looks wrong. Nouri is iPhone (iOS only), and you can try it free.

Most mornings I do not even pick up the phone: "Hey Siri, track food in Nouri," then "my usual oats with a banana," and the numbers appear on the lock screen while I eat. If I build something fancier, a photo of the bowl gets itemized the same way, and I add the scoop size the camera cannot know.

On Sunday evening the week of breakfasts shows up in my Nouri Report: average protein against my target, how many days I hit my goal, and one clear focus. When the focus says protein, that is my cue to add eggs to the oats, not more peanut butter.

FAQ

How many calories in a cup of oatmeal?

About 166 calories if you mean a cup of cooked oatmeal made with water, and about 307 if you mean a cup of dry oats. The dry measurement is the reliable one, because the cooked figure depends entirely on how much water you added.

How many calories in 1/2 cup of dry oats?

About 153 calories, with 5.3g of protein and 4.1g of fiber, per USDA data. This is the standard serving most people actually make.

How many calories in a packet of instant oatmeal?

A plain instant packet is 28g, which is about 101 calories. Flavored varieties add sugar, so read the specific box rather than assuming the plain number.

Is oatmeal good for weight loss?

The base is favorable: 153 calories for a serving with 4g of fiber that stays with you. What decides the outcome is the assembled bowl, since toppings commonly double or triple it, and your overall deficit as covered in Calorie Counting 101.

How many calories in oatmeal made with milk?

Take the dry-oat number and add the milk as its own food. A cup of whole milk is about 149 calories by USDA data, so a half-cup serving of oats made with a cup of whole milk lands near 302 before any toppings.

How much protein is in oatmeal?

About 5.3g per half-cup dry serving, or 10.7g in a full cup of dry oats. That is decent for a grain and low for a breakfast, so most people pair it with whey, eggs, or Greek yogurt.

Are steel-cut oats lower in calories than rolled oats?

Per dry gram they are essentially the same food, because the cut changes texture and cook time, not energy. Steel-cut oats often seem lower because they expand more in water, so a cooked cup holds less oat.

How many calories in overnight oats?

Start with the dry oats, usually 40g to 50g for 152 to 190 calories, then add every other ingredient separately: milk or yogurt, seeds, fruit, sweetener. Overnight oats are a mixing bowl, so the honest log is the ingredient list, not the dish name.

Is oatmeal high in fiber?

Yes by breakfast standards: 4g in a half-cup dry serving, and 8.2g in a full dry cup. Rolled oats are 10.1g of fiber per 100g dry.

How many carbs are in oatmeal?

About 27g per half-cup dry serving, of which roughly 4g is fiber. A cup of dry oats carries about 55g of carbs.

Does oatmeal have more calories dry or cooked?

Neither. Cooking only adds water, so the calories in your bowl were fixed the moment you measured the oats. The per-cup numbers differ because a cup of porridge contains far less oat than a cup of dry flakes.

How many calories in oatmeal with banana and peanut butter?

About 449 by the verified component math above: 153 for a half-cup of dry oats, 105 for a medium banana, 191 for two level tablespoons of peanut butter.

What is the easiest way to track calories in oatmeal?

Type the bowl into Nouri like a note, oats plus every topping, or tell Siri. Calories and macros come back instantly, itemized with the reasoning shown, and your weekly Nouri Report shows how those breakfasts added up across the week.

Measure the dry oats once with whatever scoop you already use, then let the toppings be the thing you actually describe. One sentence in Nouri itemizes the bowl so you can see which part earned its calories, Greek yogurt and apple numbers cover the usual toppings and sides, and Calorie Counting 101 covers where your daily target should come from in the first place.

Sources

• USDA FoodData Central, SR Legacy: Cereals, oats, regular and quick, not fortified, dry (FDC 173904); Cereals, oats, regular and quick, unenriched, cooked with water, without salt (FDC 173905); Cereals, oats, instant, fortified, plain, dry (FDC 171661), fdc.nal.usda.gov (checked September 27, 2026)
• USDA FoodData Central, SR Legacy: Honey (FDC 169640) and Milk, whole, 3.25% milkfat (FDC 172217), for the topping and milk figures (checked September 27, 2026)
• Portion weights are USDA's own household measures; per-portion values calculated from USDA per-100g figures times those weights
• Banana and peanut butter figures from our banana and peanut butter guides, both USDA-sourced