What is Stack Height? Here’s Why It Matter in Running Shoes

Stack height is an important factor that will affect how your running shoe feels. It refers to the amount of cushioning material that separates your foot from the ground. Specifically we are focused on the stack at the heel, which will then impact the heel to toe drop and whether the shoe is considered low stack or maximal.The Vomero Premium is an easy to understand example of a max stack height shoe. It’s a beehomoth of cushion underfoot.

But what is the ideal running shoe stack height and why does it matter?

Many people confuse it with heel to toe drop and use those terms interchangeably. They aren’t interchangeable, but no worries we will make these easy to underestand and you’ll be a shoe expert in no time.

What is Shoe Stack Height?

When it comes to running shoes, one of the most important factors to consider is the stack height. Stack height refers to the amount of cushioning material that separates your foot from the ground. It’s an important element in determining the degree of shock absorption and foot protection that the shoe offers.

This used to be referred to as a maximal shoe (HOKA) or a minimal shoe (Altra).

The stack height is determined by measuring the total height of the midsole, including the foam, air chambers, and other cushioning materials, from the ground to the insole’s surface.

The higher the stack height, the more cushioning. In contrast, a lower stack height means less cushioning and a more direct ground feel.

Is there a perfect stack height?

No.

But it can make a huge difference in how the shoe works for you. While our brains very quickly adapt to the higher stack, hence picking up our feet not to trip, it may take the tendons and muscles more time. I’ve seen a lot more ankle soreness since folks moved to wearing max cushioned running shoes all the time.

Similarly if you’ve been in a high stack shoe and suddenly go to less cushion and zero drop the calves get overworked.

Once again going back to the study that showed a good running shoe rotation reduces injury risk!

Stack Height Categories

Based on stack height, here are some main categories of running shoes, these numbers have changed over the last few years. What was once considered moderate daily trainer at 19mm is now very much a low stack height shoe because max cushioned shoes are all 40mm+.

When Hoka first launched at 32mm it was considered a massive shoe, so massive that runners laughed and wouldn’t wear it. Now it’s a moderate shoe!

We’ll link to round ups of shoe examples where we have them below to help you find styles in that range.

Barefoot: These have the lowest possible stack height at 1 – 8mm. They’re best for limited use for speed work or strides, or running on soft surfaces like even grass.

Minimal: These have a stack height of 9 – 13mm and are usually used for faster training or if you’re looking for a minimalist running experience.

Low Stack: These have a stack height of up to around 30mm. Most often these are lighter shoes and great for shorter races, but some folks also just prefer less cushion. Is this technically a category?? Ehh so so, but I do find that there’s a difference in the shoe at 29mm like the Kinvara and the daily trainer at 38mm.

Medium Stack: These have a stack height of 32 to 39mm. This is the moderate cushioned daily trainer and honestly by the time we hit 39mm we are getting in to a very well cushioned shoe.

Max Stack: These have a stack height of more than 40mm. They’re best for long runs and are also a great option for easy runs or recovery runs. This is also what you will find in more and more carbon fiber super shoes, as they are trying to maximize cushion.

You’ll notice that most carbon plated running shoes are max stack. That’s because the combination of the running shoe foam used with the plate creates the most bounce and energy efficiency.

How to Measure Stack Height in Running Shoes

Measuring stack height is an important aspect of understanding the performance and comfort of your running shoes. It can help you determine whether a shoe is suitable for your running style, as well as provide insight into the shoe’s durability and support.

To measure stack height, you can follow these simple steps:

1. Remove the insole of the shoe to expose the midsole. Some debate on this, but most remove the insole
2. Use a caliper or a tape measure to measure the distance between the ground level and the midsole’s highest point (very specifically 12% from the end of the shoe). This measurement represents the heel stack height.
3. The same process is then done at the forefoot to provide the lowest stack height and that’s how the heel to toe drop is calculated.

It’s important to note that stack height can differ between the heel and the forefoot of the shoe. This will be true in all running shoes that are not zero drop running shoes.

Checkout this article to better understand how heel to toe drop plays a role in knee pain or reducing issues like Achilles pain.

Stack Height vs Heel Drop

When it comes to choosing the right running shoe, stack height and heel drop are two essential factors to consider. Though honestly they’re overlooked because we’re drawn in by colors and flashy things! Now you’ll know more to find what actually works best for you.

Heel drop, offset, or heel-toe drop refers to the difference in stack height between the heel and forefoot of a shoe.

A higher heel drop means that the heel is elevated more than the forefoot, while a lower heel drop means that the heel is closer to the ground. Envision a high heeled shoe for a drastic example.

On the other hand, stack height is measured from the ground to the insole’s surface and is the total thickness of the midsole. It includes the heel and forefoot, and it’s usually expressed in millimeters as well.

A higher stack height means that there is more cushioning and protection between your foot and the ground, while a lower stack height offers a more minimalistic feel.

How Stack Height and Heel Drop Affect Runner’s Gait

While these two factors are related, they have different effects on a runner’s gait, in theory. The reality is that a great deal of it comes down to your stride and how you run. Some people will benefit from the cushion of a high stack height and others will simply overstride more as it masks what they are doing.

The stack height of a shoe also plays a crucial role in determining how it feels when you run. A higher stack height provides more cushioning and protection, which can be beneficial for runners who need extra support or have a history of injuries.

However, it can also make the shoe feel bulky and less responsive. We’re also seeing some data that running in max cushioned shoes all the time may result in higher impact on landing, we don’t yet know the result of that and need more studies.

A lower stack height, on the other hand, offers a more direct ground feel, which can be ideal for runners who prefer a minimalist shoe and want to feel more connected to the ground.

Stack Height and Ground Feel

The ground feel is an important factor for runners to consider and particularly important for trail runners, which is why we’ve seen a lot more low and moderate shoes stick around compared to the roads.

A higher stack height can reduce the ground feel and provide more cushioning, which can be beneficial for runners who are looking for a more comfortable and forgiving ride. We also believe that additional cushion helps the legs to recover faster by reducing the impact.

On the other hand, some runners prefer a lower stack height, as it provides a more natural gait and responsive feel. When the foot is closer to the ground, it can better sense the terrain and adjust accordingly.

This can help improve balance, stability, and agility, which can be especially important for trail runners who need to navigate uneven and unpredictable terrain.

It’s worth noting that the stack height isn’t the only factor that affects the ground feel. The type and density of the midsole foam, as well as the outsole design, can also play a role.

For example, a shoe with a thick midsole but a firm outsole may still provide a relatively low ground feel, while a shoe with a thin midsole but a soft outsole may still provide a relatively high ground feel.

Pros and Cons of Running Shoes with Different Stack Heights

There are different pros and cons to running shoes with varying stack heights. So let’s look at the same advantages and disadvantages of high and low stack height shoes to help you figure out which one will be best for your personal preferences:

High Stack Height

Pros:

• Greater cushioning and shock absorption
• Improved recovery from more cushion
• Improved comfort for runners with heavier builds

Cons:

• Less ground feel and reduced sense of connectedness with the running surface
• Reduced stability due to a higher center of gravity, leading to trips and falls
• Higher energy expenditure due to increased weight and shoe stiffness

Low Stack Heights

Pros:

• Improved ground feel and increased sense of connectedness with the running surface
• Improved stability due to a lower center of gravity, leading to fewer trips and falls
• Reduced energy expenditure due to lower weight and shoe flexibility
• Potential for faster times due to less shoe resistance against the running surface

Cons:

• Less cushioning and shock absorption
• Increased risk of injuries caused by insufficient impact protection
• May not be suitable for runners with heavier builds or those with a tendency for heel striking
• May cause discomfort and pain in the feet and joints due to the diminished cushioning

What to read next?

• Best HOKA running shoes
• Best ALTRA running shoes
• Best wide toe box running shoes