How much fiber is in oats?
Oats has 4.2 g of fiber per 1/2 cup dry (40 g) — about 15% of the 28 g Daily Value. That's 10.6 g of fiber per 100 g.
USDA FoodData Central · dry rolled/old-fashioned · FDC 169705
Fiber by portion
| Portion | Fiber | % DV | Total carbs | Net carbs | Calories |
|---|---|---|---|---|---|
| 1/2 cup dry (40 g) | 4.2 g | 15% | 26.5 g | 22.3 g | 156 |
| 100 g | 10.6 g | 38% | 66.3 g | 55.7 g | 389 |
| 1 oz (28 g) | 3 g | 11% | 18.8 g | 15.8 g | 110 |
% DV against the FDA Daily Value of 28 g of fiber. Net carbs = total carbs − fiber, since fiber isn't digested like other carbs. Values from USDA per-100 g data (FDC 169705, SR Legacy). dry rolled/old-fashioned.
A bowl of oatmeal is one of the most reliable ways to start the day with fiber. A standard 1/2-cup dry serving (40 g) — the scoop most people actually cook — carries about 4.2 g of fiber, roughly 15% of the 28 g Daily Value, from 10.6 g per 100 g. Cooking doesn’t change that: simmering or soaking only adds water, so the bowl in front of you holds the same ~4.2 g the dry scoop did. Anchor to the dry weight, not the volume of the finished bowl, and oats are a dependable fiber base you can build on every morning.
Beta-glucan: the fiber that makes oats special
Oats’ claim to fame is beta-glucan, a specific soluble fiber. Soluble fiber dissolves into a gel that slows digestion and feeds gut bacteria — and beta-glucan is the type most associated with heart-healthy eating patterns, which is why oats carry that reputation. It’s also what gives cooked oatmeal its thick, creamy body: that texture is the fiber at work. Oats bring some insoluble fiber for bulk as well, but the soluble beta-glucan is the headline, and it’s the reason a bowl feels filling and steady rather than quickly hungry-again.
On the carb side, oats are a different animal from a low-carb food like nuts or chia, and it’s worth being honest about that. A 1/2-cup dry serving has about 26.5 g of total carbohydrate, of which ~4.2 g is fiber — so net carbs land around 22.3 g. Fiber is always the carb you subtract, but oats are mostly slow-digesting starch, so the net number stays high. The fiber and the slow starch together are what make oats a steady-energy breakfast that releases over hours rather than spiking — they’re a slow-carb-and-fiber food, not a keto one.
Hitting your fiber goal with a bowl
The practical value is momentum: most people get only about half the 28 g daily target, and a breakfast that opens with ~4.2 g of fiber puts you ahead before lunch. Toppings compound it fast — a handful of berries, a spoonful of chia, or some almonds can push a single bowl past 8-10 g of fiber. Build the habit around the dry scoop, treat oats as the canvas, and let high-fiber add-ons stack on top. It’s one of the lowest-effort ways to make a real dent in the day’s number.
Oats also bring a modest amount of plant protein, and pairing them with milk or yogurt raises it. For that side of the picture, see protein in oats.
Packaged oats & oatmeal options, graded
Prefer something off the shelf? Here are the best-graded oats & oatmeal in our catalog — each scored on our transparent Labelgrade. Check the fiber line on each label.
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Labelgrade 80/100 · 3 g fiber · 12 g protein
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Frequently Asked Questions
How much fiber is in oats?
About 4.2 g of fiber in a 1/2-cup dry serving (40 g), the standard scoop most people cook, which comes from 10.6 g per 100 g (USDA FDC 169705). Cooking doesn't change the grams — it only adds water — so a bowl made from that scoop still has ~4.2 g of fiber.
What percent of the daily value for fiber is in a serving of oats?
About 15% of the 28 g FDA Daily Value from a 1/2-cup dry serving. A bowl of oatmeal is a strong way to open the day on fiber, and toppings like berries, nuts, or chia push the number higher.
What kind of fiber is in oats?
Oats are famous for beta-glucan, a soluble fiber. Soluble fiber dissolves into a gel that slows digestion and feeds gut bacteria; beta-glucan in particular is the fiber most associated with heart-healthy eating patterns. Oats also carry some insoluble fiber for bulk. The beta-glucan is what gives cooked oatmeal its thick, creamy texture.
What are the net carbs in oats?
Oats are a higher-carb whole grain. A 1/2-cup dry serving has about 26.5 g of total carbohydrate, of which ~4.2 g is fiber, so net carbs land around 22.3 g. Fiber is the carb you subtract, but oats are mostly slow-digesting starch — they're a steady-energy food, not a low-carb one.
Do steel-cut, rolled, and instant oats have different fiber?
Per gram, they're essentially the same — steel-cut, rolled (old-fashioned), and plain instant oats are the same grain, just cut or rolled differently, so the fiber is nearly identical. Watch flavored instant packets, which are smaller portions and may list less fiber per packet than a full 1/2-cup scoop.
When was this data last verified?
2026-06-04, against USDA FoodData Central FDC 169705 (Oats; SR Legacy). We re-verify reference pages periodically and update when USDA revises its values.
Whole-food values are USDA reference data, not a Labelgrade (that score is for branded packaged products). See our methodology and the carbs & net carbs lane.