What Do Heel Drop and Stack Height Mean and Why Should Runners Care?
When choosing the best running shoe for your needs, understanding terms like “heel drop” and “stack height” can provide valuable insights into how the shoe will perform and feel during your runs. These characteristics can vary between different running shoe models and brands, and they play a significant role in how the shoe interacts with your foot and the ground. Let’s break down what these terms mean and why they differ:
Heel Drop (or Offset)
Heel drop (aka offset or drop) refers to the difference in height between the heel and the forefoot of the shoe. It’s typically measured in millimeters and is often presented as a single number, such as “10mm heel drop” or “4mm heel drop.”
A higher heel drop means that the heel is positioned higher off the ground than the forefoot. Conversely, a lower heel drop means that there’s less height difference between the heel and the forefoot.
Heel drop affects the angle of your foot within the shoe during running. A higher heel drop can encourage a more heel-striking running style, where your heel makes initial contact with the ground first. A lower heel drop may encourage a more midfoot or forefoot strike.
Stack Height (or Stack Height Ratio)
Stack height refers to the amount of cushioning material underfoot, from the outsole (bottom of the shoe) to the insole (footbed). It’s often measured in millimeters, and you might see specifications like “25mm/20mm stack height” or “full-stack cushioning.”
The stack height can be different in the heel and forefoot areas, resulting in a stack height ratio. For example, a shoe with a 25mm/20mm stack height ratio means that the heel has 25mm of cushioning, and the forefoot has 20mm.
Stack height impacts the overall comfort and cushioning of the shoe. A higher stack height typically provides more cushioning and impact absorption, which can be beneficial for longer runs or those looking for a plush ride. A lower stack height may provide a more responsive and natural feel, ideal for those seeking a closer connection to the ground.
There are positives and negatives to both. The higher the stack height, the greater the potential for ankle roll and the heavier the shoe becomes. At the low end of stack height, your feet may feel like they took a beating at the end of a long run on either pavement or trail.
Runners have different strike patterns—heel, midfoot, or forefoot—which influence the ideal heel drop. Some runners may benefit from a higher drop to accommodate a heel-striking gait, while others might prefer a lower drop for a more natural midfoot or forefoot strike. It’s not uncommon for runners with a heel-strike gait to choose a lower drop shoe to encourage a move away from heel-striking. However, if you plan on doing this, don’t make drastic changes. Ease into these changes or you may injure yourself.
The type of terrain you’ll be running on can also affect the ideal heel drop and stack height. For example, you may prefer a slightly higher stack height when choosing a trail running shoe to absorb some of the feel of hard, rocky surfaces. On the opposite end, if you do most of your running on a track, you can choose a lighter weight shoe which dispenses with the additional cushioning.
When running very long distances during training or racing, some people prefer more cushioning, leading to a significantly higher stack height. Some shoe designs increase the heel drop at the same time, but there are plenty of very cushioned shoes with zero drop. If you typically run shorter distances or all your training is speed-focused, go with a low stack height to save weight.
Foot and Running Mechanics
Different foot shapes and mechanics require varying levels of support and cushioning. Most runners can figure out what works best for them on their own. However, if you have pain or any discomfort while running, you may want to consult with a medical professional before attempting to solve the problem by trying different shoes that might make the problem worse.
Keep in Mind
Remember that personal comfort and fit are key factors in selecting the best running shoe for you. What works for your friend on someone posting a shoe rec on social media might not be best for you, your feet, or your running needs. At the same time, don’t become fixated on your shoes as a replacement for lack of training or poor running habits. At the end of the day, running is about… running (duh!), and it has been shown over and over that you don’t need special snowflake shoes to do it.