Understanding Stack Heights in Running Shoes

Before you dive into our running shoe guide, it’s important to understand the variety of options available for stack height in running shoes these days.

Take a look at any running shoe store shelf and you’ll notice a huge range of midsole thicknesses. Some shoes are fat and cushy, with the midsole—the soft foam cushioning layer between the outsole and upper that wraps around your foot—resembling a Double Stuf Oreo or marshmallow. (And, yes, there’s only one “f” in “Double Stuf.”) These types of shoes are generally referred to as “maximalist” shoes, or shoes with “maximal” cushioning. Other shoes look more streamlined, with less cushioning (like a regular Oreo), or with barely any visible cushioning at all. These are generally referred to as “minimalist” shoes.

RELATED: Moving Beyond Pronation Control in Running Shoes

The amount of cushioning, in shoe-geek speak, is called the “stack height.” It refers to how high the shoe’s midsole foam is “stacked” between the ground and where your foot sits within the shoe. For most shoes, stack heights are slightly higher under the heel than under the forefoot. It’s not uncommon to see stack heights listed as “33mm/28mm” (on the maximal side) or “23mm/17mm” (more minimal), for instance. Sometimes you’ll only see the “heel offset,” which only tells the difference between the heel and forefoot—a measurement many shoe experts use to address the way your foot strikes the ground. (When there is no difference between the stack under the front and back of the shoe, that’s what’s known as a “zero drop” shoe.)

“If you go by industry standards, everything above 28mm is considered max cushioning,” said Mark Plaatjes, world-champion marathoner, physical therapist, and owner of Boulder-based In Motion run specialty store. But, Plaatjes explained, there’s a new breed of shoes which appear minimal, but still achieve the feeling of generous cushioning—due to unique compounds that maximize a bouncy, cushy feeling without a massive amount of foam material.

Conversely, the relatively new breed of “super shoes” on the market combine maximal cushioning with a carbon plate, a unique construction worn by runners breaking virtually every speed record over the past few years. In other words, high-stack shoes are no longer pigeon-holed as recovery shoes, or shoes for injured runners. And shoes that look more like racing flats may deliver a surprising amount of bounce.

Plus, cushioning is subjective. “You can steer someone who you think needs max cushioning to a high-stack shoe, and they think it feels hard,” Plaatjes said. “Or you put someone in what you think is a firm shoe, and they like the cushioning.”

Plaatjes generally offers maximally cushioned shoes to those who exclusively run on pavement, larger runners, and people who have what he calls “a rigid foot.”

“Typically, people with high arches and rigid feet need high cushioning because their feet don’t flex like someone who pronates, and everything goes up the chain. Those people may have shin splints, knee, hip, or low back issues.”

Still, Plaatjes is quick to add that the ideal amount of cushioning for each runner—and which specific shoe, for that matter—isn’t black and white. To find the right shoe for you, visit a specialty retailer, and have a knowledgeable salesperson ask you questions and watch you run in a range of shoes. Also, be sure to check out our shoe guide to give you a jumping off point to begin the conversation.

Ready to lace up some new shoes? Check out our Running Shoes Guide.