Carbon Steel vs. Cast Iron: What’s the Difference Between These Cookware Darlings? (And What’s Carbon Steel in the First Place?)

Carbon steel cookware (like this skillet from Misen) is made from an alloy, aka a mixture of two or more metals or a metal combined with another element. In this case, it’s carbon and iron. To be classified as steel, it can’t contain more than two percent carbon—for example, stainless steel contains 1.2 percent carbon, and carbon steel contains exactly two percent.

Unlike shiny stainless steel, carbon steel is matte until it’s seasoned. It’s also extremely hard (and a popular material for kitchen knives, because it stays so sharp). Because of the extra strength from the iron, carbon steel can be manufactured thin and lightweight, making it as ideal for quickly sautéing vegetables as it is for searing steaks. It has a smooth surface that’s as slippery as a nonstick pan when seasoned properly. And up until recently, it was really only well-known in restaurant kitchens and among the most serious home cooks (looking at you r/carbonsteel).

The only downsides? Carbon steel can rust and corrode (just like cast iron), and the seasoning can scratch off if you take a metal utensil to the surface.

How do you care for carbon steel?

Raw carbon steel is a rust magnet, so you’ll need to season it regularly to keep it in working condition. The process is just like seasoning cast iron: Coat it in an ultra-thin layer of neutral oil and get it searing hot; repeat until it’s slippery and shiny. These days, you can buy cast iron pans pre-seasoned, but you’re less likely to find a carbon steel pan that doesn’t require seasoning before the first use.

To clean carbon steel cookware, simply wash it gently with dish soap (skip the abrasives and the dishwasher), dry it thoroughly and apply a light layer of oil to maintain the seasoning between uses.

Cast iron is also alloy of iron and carbon, but with more carbon content than steel—usually two to three percent. The higher carbon content makes it rough, bumpy and brittle, and it’s also why it’s manufactured so thick and heavy. If cast iron was thin, it would be prone to breakage.

The extra carbon in cast iron makes it a poor heat conductor: It takes a long time to heat up on the stove, and when it’s hot, it stays hot for a long time. That heat retention makes it excellent for searing meat and seafood, and getting a golden-brown crust on cornbread, but it’s also pretty heavy to lift—no cheffy flicks of the wrist to sauté a batch of green beans here.

To extend the life of your cast iron, you’ll have to season it periodically (just like carbon steel). Gently handwashing with soap and water and a thorough dry-off will prevent rust and maintain that hard-earned seasoning.

Carbon steel vs. cast iron: What’s the difference?

Carbon steel and cast-iron cookware are made of the same metal alloy and require similar care, but otherwise, they’re pretty different:

• Carbon steel contains less carbon than cast iron, and it’s thin, lightweight and smooth. It’s more heat conductive, so it heats up fast and even and has few hot spots. The smooth surface makes it more nonstick than cast iron; it can be as slick as a nonstick pan when seasoned properly.
• Cast iron has a higher carbon content than carbon steel, so it’s bumpier and more brittle. To resist breakage, cast iron pans are thicker and heavier—this makes them poor heat conductors but good at retaining heat.

Which pan is best for which job?

The slight differences between carbon steel and cast iron make them each ideal for specific tasks in the kitchen.

• Because it’s so lightweight, carbon steel is suitable for sautéing or any cooking that requires maneuvering the pan. (Your forearms will thank us.) It’s also more nonstick than cast iron, so go ahead and fry eggs (or any sticky food) in it. And since carbon steel heats up fast and even, you can use it to get a handsome brown sear on a steak or chop.
• Cast iron is heavy and slow to heat up, but that makes it ideal for searing a steak in minutes or making a crispy-edged smash burger on the stovetop. It’s also oven-safe and great for baking (especially bread). Cast iron is super durable and when cared for properly, will last a lifetime.
• It’s worth mentioning that you should avoid cooking acidic foods (like tomato sauce) for long periods of time in both carbon steel and cast iron, since the acid can cause the seasoning to erode. And with both pans, this erosion can cause metallic particles (like iron) to be released into the food—but according to America’s Test Kitchen, it’s not a significant enough amount to affect your diet.