Ever get overwhelmed staring at all the different types of oatmeal in the store? Should you get steel-cut oats, rolled oats, or old-fashioned oats (or are some of those the same thing)? Which one is healthier, and can you use them all interchangeably? Here’s what you need to know.
If you’re going to eat oatmeal, you might as well eat the kind not stripped of its nutrition. Especially if you’re feeding it to kids. But hey, you matter too. So what is the difference between steel-cut, Scottish, Irish, rolled, quick-cooking, old-fashioned, and instant oats?
Short answer: Some are milled differently, while others are exactly the same but called different names.
Speaking of, what is the difference between oats and oatmeal? Technically, oats refers to the whole grains themselves, and oatmeal to the porridge-like dish often made from them, and/or to the processed form of the whole grains—but now, the terms are often used interchangeably.
The Finer Points of Processing
For every type of oatmeal, the oats first undergo cleaning, hulling, and conditioning, which removes the outer shell (called a hull), leaving the inner kernel or oat groat. The groat is then brushed clean in scouring machines. Next, a kiln heats the groats to about 215 degrees Fahrenheit to deactivate their enzymes, which limits how the oils present in the germ can react with oxygen, making the oats stable for storage, as well as giving them a slightly toasty flavor. Chelsea Lincoln, a representative from Bob’s Red Mill Natural Foods, says this is important because “oats go rancid very quickly if not stabilized.”
Related Reading: How to Make Savory Slow Cooker Oatmeal
From there, the whole oat groats are processed differently depending on what type of oatmeal they are being made into:
Steel-Cut Oats (a.k.a, Irish Oats)
Lincoln says that to make steel-cut oats (also known as Irish oats), the groats are chopped up with steel blades. “This allows for a chewier oatmeal,” says Lincoln. They take about 30 minutes to cook.
Stone-Ground Oats (a.k.a, Scottish Oats)
For stone-ground oats (also called Scottish oats), the groats are ground into a meal, which makes a “porridge-type oat with a nice, creamy texture.” Like Irish oats, Scottish oats take around 30 minutes to cook.
Rolled Oats (a.k.a, Old-Fashioned Oats)
Rolled oats (also known as old-fashioned oats) take less time to cook and have a less coarse and chewy texture. To make them, the groats are softened by steaming, then run through metal rollers to flatten them. Lincoln says that Bob’s Red Mill regular rolled oats are flattened to 0.024 to 0.032 inches.
Instant Pot Duo, $79 on Amazon
Quick-cooking oats are rolled even thinner—about 0.017 to 0.022 inches—so they will cook in under five minutes.
Instant oats are also rolled thin, but are then “cooked and then dried again,” says Lincoln. Just add hot water and stir.
Which Type of Oats Are Healthiest?
All oats are quite healthy for you; they’re full of soluble fiber, vitamins, and minerals. Compared to other breakfast cereals and many other grains, they’re also low on the glycemic index, meaning they will take longer to digest and will have a lower impact on blood sugar levels (they’re considered a good carb). The less processed the oats are, the more nutrition they retain. And you should watch out for added sugar and preservatives in instant oatmeal.
Oats are naturally gluten-free, but are often processed in facilities that handle flour, so cross-contamination can be an issue. Be sure to look for a certified gluten-free label if you have celiac disease or gluten intolerance.
Can You Use Different Types of Oats Interchangeably?
Most recipes that call for oats specify rolled oats or old-fashioned oats (which, remember, are the same thing), but you can also use quick-cooking oats interchangeably. There may be minor changes to the texture, but it’s not usually so noticeable as to be a dealbreaker.
In a pinch, instant oats can also usually be used in place of the above in things like oatmeal cookies (where they’re fully mixed into the batter), but the texture will be even softer and the cook time may be significantly shorter, so be sure to check for doneness sooner. They’re not a good swap in homemade granola or in recipes where the oats are used for a crumbly, crunchy topping.
Irish and Scottish oats won’t work in place of other types of oats since they’re much more chewy and firm, so look for steel-cut oat recipes when you want to use them in particular.
Making your own granola for topping yogurt or simply snacking is usually a lot healthier and sometimes more economical than buying it at the store (but it depends on what you want to add in). Get our Easy Homemade Granola recipe.
These are chewy, sweet, soft, and a little crunchy on top with the oat crumble. And they’re easy to make with ingredients many of us keep on hand already so there’s no hunting down a random ingredient at the store. Get our Apple Oatmeal Bars recipe. (Try our Apricot Oatmeal Bars recipe too.)
Toss the ingredients into your Crock-Pot right before you go to bed and wake up to some creamy, warm breakfast. Just add vanilla, nuts, and fruit—fresh or dried. Get our Slow Cooker Steel-Cut Oatmeal recipe.
Wait, what? Oh, yes. These are especially great during the summer, when you don’t want to heat up your kitchen more than it is already. It takes 15 minutes to make, plus cooling time. These cookies taste of chocolate and peanut butter too, and we love that. Get our No-Bake Oatmeal Cookies recipe.
This is what your summer is missing: Peaches and raspberries encased in a crust and topped with an oat-brown sugar streusel. Serving this pie with a scoop of good vanilla ice cream is a must. Get our Peach Melba Pie recipe.
These are perfect when you’re craving Girl Scout cookies out of season. We call for quick-cooking oats here to keep the texture nice and soft. Get our Do-Si-Do Copycat Cookie recipe. (For more upgrades on the usual oatmeal raisin, try our tropical Oatzravaganza Cookies recipe and our chewy Peanut Butter Chocolate Chunk Oatmeal Cookie recipe too.)
You don’t have to cook this at all! The rolled oats absorb the milk and get soft with time. Now that’s easy. Dump the ingredients in a bowl or jar the night before, refrigerate, and then take it out the next morning, top it with fresh fruit, and eat. Get our Overnight Oats with Summer Fruit recipe.
Another unusual thing to do with oatmeal? Steep it in vodka for a toasty-sweet tipple! Get our Oat and Honey Vodka recipe. (If you don’t drink alcohol, you can try making oat-infused milk…not to be confused with non-dairy oat milk, but still delicious.) Sip it straight or try it cut with cream in our Quaker Shaker recipe.
See all of our oat recipes for more.
Originally written by Roxanne Webber in 2008; updated by Amy Sowder.
Header image courtesy of Westend61/ Getty Images