Steel-Cut Oats

One US cup of steel-cut oats weighs 160 grams. Going the other way, 100 grams is about 0.62 cups.

Also called steel cut oats, steel-cut oats, Irish oats, pinhead oats, Irish steel cut oats, coarse cut oats.

One cup of dry steel-cut oats weighs about 160 grams (0.676 g/mL). USDA FoodData Central FNNDS record 2346397 lists 1/4 cup dry = 40 grams. McCann's Steel Cut Irish Oatmeal, Great Value Steel Cut Oats, Heartland Steel Cut Oats, and every other mass-market producer label matches at 40 grams per 1/4 cup — full convergence with USDA. Two notable outliers exist and are worth understanding: Bob's Red Mill lists 45 grams per 1/4 cup (181 g/cup) because they cut finer than the standard 2-3-pieces-per-groat profile, and King Arthur Baking's chart lists 140 g/cup from their spooned-and-leveled measurement method.

Steel-cut oats (also known as Irish oats or pinhead oats) are whole oat groats chopped by a sharp-bladed machine into coarse pieces before any steaming, so they retain the intact bran layer and the original cell-wall structure of the oat. This is what distinguishes them from rolled oats (steamed then flattened between rollers) and quick oats (rolled thinner and cut into smaller flakes). The intact groat structure gives steel-cut oats a lower glycemic index (about 42-55 versus 55-69 for rolled and up to 75 for instant), a chewier finished texture, and a longer cook time (20-30 minutes on the stovetop versus 5 minutes for rolled).

Brand cut variance is the main density driver worth knowing about. McCann's describes their traditional steel-cut oats as groats cut into only 2-3 pieces, which produces the coarsest common cut on the US market and lands at 160 g/cup. Great Value, Heartland, and most store brands match this cut profile. Bob's Red Mill uses a steel burr mill that cuts finer, producing more but smaller pieces per groat — the finer cut packs denser into a measuring cup and reads 181 g/cup on their own label, about 13% heavier than the standard-cut convergence. This is not a measurement error and it is not the classic King Arthur fluid-ounce error either; it is genuine physical product variance. Bakers who switch brands mid-recipe should weigh, especially between McCann's-profile and Bob's-profile products.

King Arthur Baking's Ingredient Weight Chart lists steel cut oats at 1/2 cup = 2.5 oz = 70 g, reading out to 140 g per cup. This is about 14% below the USDA anchor. KA's chart methodology instructs bakers to 'spoon dry ingredients gently into the cup and sweep off any excess,' which for a dense granular product can leave more air in the cup than scooping directly from the package. The KA figure is internally consistent with their measurement method but does not match what most bakers do in practice (scoop the measuring cup directly into the oat container). For weight-based cooking or baking, the USDA + producer label figure of 160 g/cup is the more practical anchor.

Cooking ratios are consistent across brands regardless of density: 1 part dry steel-cut oats to 3-4 parts water, cooked at a simmer for 20-30 minutes, yields about 3 cups of cooked oatmeal per 1 cup of dry oats. Quick-cooking steel-cut oats (Bob's Red Mill and McCann's both make these) are the same product par-steamed to shorten cook time to 5-8 minutes — they weigh the same per cup dry as the traditional version from the same brand. Rolled oats and steel-cut oats are not one-to-one substitutes: rolled oats absorb water faster and produce a softer, creamier finish, while steel-cut hold their chewy structure through longer cooking. For baking applications (granola bars, oat cookies), rolled oats or quick oats are almost always the right choice; steel-cut are too coarse and cook too slowly to soften properly during typical bake times.