Running Shoe Drop Explained: 0 mm, 4 mm, 6 mm, 8 mm — What Does It Actually Mean?
Look at the specifications of almost any running shoe and somewhere among the foam names, stack heights and technical features you will find another number: 8 mm drop.
Or perhaps 6 mm. 4 mm. Maybe even 0 mm.
For something that sounds quite technical, heel-to-toe drop is actually a simple measurement. The harder part is understanding whether it matters to you.
A lower-drop shoe is not automatically more natural. A higher-drop shoe is not automatically more supportive. Zero drop is not inherently better. And there is no single number that every runner should be aiming for.
So rather than starting with what the internet says you should run in, let’s start with what drop actually means.
What is heel-to-toe drop?
Heel-to-toe drop is the difference in height between your heel and your forefoot when you are standing in the shoe.
Imagine a shoe where your heel sits 38 mm above the ground and your forefoot sits 30 mm above the ground. The difference is 8 mm. That makes it an 8 mm drop shoe.
If the heel and forefoot sit at the same relative height, the shoe has a 0 mm drop.
Importantly, drop does not tell you how cushioned a shoe is. A shoe can be zero drop and still have plenty of foam underneath your foot. Equally, a shoe with an 8 mm drop does not necessarily have more cushioning.
Drop and cushioning are two different things.
A simple way to picture it
Think of drop as the difference in height underneath your heel compared with your forefoot:
- 0 mm: heel and forefoot sit at approximately the same relative height.
- 4 mm: the heel sits 4 mm higher than the forefoot.
- 6 mm: the heel sits 6 mm higher.
- 8 mm: the heel sits 8 mm higher.
Visual guide: what different shoe drops look like
If heel-to-toe drop feels abstract, this illustration makes it easier to see. Remember: drop is the difference in height between heel and forefoot — not the total amount of cushioning in the shoe.
As the number increases, the difference between the rear and front of the foot increases. But that does not mean one end of the scale is better than the other.
What difference does drop actually make when you run?
Changing heel-to-toe drop can influence how your ankle, calf, Achilles tendon and knee work during running.
Broadly speaking, lower-drop shoes can increase demand around the ankle and lower leg, while higher-drop shoes can reduce some of that demand at the ankle and shift loading elsewhere. But the body does not respond according to one simple formula.
Your pace, training volume, running technique, previous footwear, strength, injury history and individual biomechanics all matter.
The useful takeaway is this: changing drop changes the environment your body is running in. That is why a significant change is worth introducing gradually.
So is lower drop better?
No. But it is not worse either.
There has been plenty of debate around lower-drop and zero-drop footwear, particularly around the idea that it encourages a more “natural” running style. The evidence does not support a simple conclusion that every runner should move towards zero drop.
Research shows that changing shoe drop can affect biomechanics, but there is no universally accepted drop that has been shown to prevent running injuries for everyone. A large randomized study comparing cushioned shoes with 0 mm, 6 mm and 10 mm drops did not find a simple overall injury-risk advantage for one drop over the others.
That moves us away from “Which drop is safest?” and towards the more useful question: “Which drop works well for me?”
What about performance?
Drop can influence running mechanics and, in controlled laboratory studies, may also influence running economy. But that does not mean a lower-drop shoe will automatically make every runner faster.
Running economy is only one part of performance. Comfort, familiarity, shoe weight, foam, rocker geometry, stiffness, training history and your ability to tolerate the shoe all matter too.
For most runners, the better question remains: does the whole shoe work well for your body and the type of running you are doing?
What do the different drops feel like?
There are no hard boundaries, but these current examples from the Xciter range make the spectrum easier to understand.
0 mm — Zero drop
In a zero-drop shoe, the heel and forefoot sit at approximately the same relative height.
A current example is the Altra Torin 8. Despite being zero drop, the Torin 8 is a highly cushioned road-running shoe. That is a good illustration of why you should not confuse drop with cushioning.
Who might enjoy 0 mm? Runners already accustomed to zero- or very-low-drop footwear, runners who enjoy a level platform underfoot, or those who prefer Altra’s traditional zero-drop geometry.
If you have spent years running exclusively in higher-drop shoes, moving immediately into zero drop can feel quite different through your calves, ankles and Achilles. That does not make zero drop dangerous. It simply means your body may need time to adapt.
4 mm — Low drop
Four millimetres still sits at the lower end of the running-shoe spectrum, but it creates a small difference between the heel and forefoot.
A current example is the Altra Experience Flow 2. Unlike Altra’s traditional zero-drop models, the Experience range uses a 4 mm drop.
That can make it an interesting option for runners who like Altra’s roomy forefoot philosophy but do not necessarily want to move straight into zero drop.
The number should never be considered in isolation. Rocker, foam and overall geometry can make two shoes with the same drop feel surprisingly different.
5–6 mm — Somewhere in the middle
Two current examples are the HOKA Bondi 9 — 5 mm and the On Cloudmonster 3 — 6 mm.
Those shoes do not feel identical. The Bondi is built around a plush, highly cushioned experience, while the Cloudmonster has a more responsive character. Yet their drops are only 1 mm apart.
That tells you something important: drop is one characteristic of a running shoe. It is not the personality of the entire shoe.
8 mm — A familiar everyday range
The HOKA Clifton 11, for example, currently uses an 8 mm drop.
For many runners coming from conventional running shoes, an 8 mm platform will feel relatively familiar. If you have been running happily and comfortably in an 8 mm shoe for years, you do not need to change simply because somebody tells you lower drop is “better”.
Does your foot strike determine your drop?
Not as neatly as some shoe guides make it sound.
You will sometimes read: heel striker = high drop and forefoot striker = low drop. Real runners do not fit into categories that cleanly.
Foot strike can be useful information, but it should not become a prescription. Your stride can also change depending on pace, fatigue, terrain and the shoe you are wearing.
Instead, look at the bigger picture: what are you running in now, is it comfortable, are you having any problems, what distances do you normally run, what are you trying to change, and what type of ride do you enjoy?
Should you change your running-shoe drop?
Sometimes. But there should ideally be a reason.
Perhaps you have found a shoe that fits your foot beautifully but happens to have a slightly different drop. Perhaps you are exploring Altra for the first time. Perhaps you are adding another shoe to your rotation. Or perhaps your current shoe simply is not working for you.
What we would not recommend is changing because someone has convinced you that your current drop is fundamentally wrong.
If you are comfortable, running well and staying healthy, that is valuable information.
If you do change drop, do it gradually
Imagine that your normal daily trainer has an 8 mm drop and you buy your first 0 mm shoe.
Do not necessarily make the new shoe responsible for every kilometre you run from day one. You might initially use it for shorter easy runs, walks or occasional runs alongside your normal shoe, and gradually increase the amount of running you do in it if it continues to feel comfortable.
There is no magic adaptation timetable because every runner is different. The practical point is to avoid changing both your footwear and your training load dramatically at the same time.
Your current shoe is one of the best clues
When we help someone choose a shoe, one of the first things worth knowing is: “What are you running in now?”
If you have just completed hundreds of comfortable kilometres in an 8 mm shoe, that is useful information. If you have been running in Altra zero-drop shoes for years and love them, that is useful too.
Your body has already given you some feedback. Do not ignore it because a specification chart tells you something else should theoretically be better.
Do not choose a shoe on drop alone
Consider these current examples:
| Drop | Xciter example | How to think about it |
|---|---|---|
| 0 mm | Altra Torin 8 | Level heel-to-forefoot platform. A significant change if you are accustomed to higher-drop shoes. |
| 4 mm | Altra Experience Flow 2 | Low drop with a small heel-to-forefoot difference. |
| 5 mm | HOKA Bondi 9 | Moderate-low drop in a plush max-cushioned shoe. |
| 6 mm | On Cloudmonster 3 | Moderate drop in a responsive cushioned platform. |
| 8 mm | HOKA Clifton 11 | A familiar everyday drop for many runners. |
Specifications are correct at the time of publication and can change between model generations. Always check the current product details.
These are not five steps along the same scale. They also differ in fit, cushioning, foam, weight, rocker geometry, width, stability and responsiveness.
A better way to use drop when choosing shoes
At Xciter, we would put drop fairly far down the decision tree.
- Choose the surface. Road or trail?
- Choose the job. Daily training, long runs, easy running, speed work or racing?
- Get the fit right. Length, width, heel security and toe room.
- Choose the ride. Soft, balanced, stable or responsive?
- Look at your current shoe. Your previous experience matters.
- Then consider drop. Is it similar to what you are accustomed to? If it is significantly different, are you happy to introduce it gradually?
For the full shoe-selection framework, read our How to Choose the Right Running Shoes guide.
Frequently Asked Questions
Is zero drop better for running?
Not universally. Some runners love zero-drop shoes. Others prefer 4, 6, 8 or 10 mm. There is no good evidence that every runner should use zero-drop footwear. Comfort, experience, training and individual response matter more than chasing one supposedly ideal number.
Is zero drop the same as barefoot running?
No. A shoe can have 0 mm drop and a substantial amount of cushioning underneath your foot. Zero drop describes the height difference between heel and forefoot, not how much material sits under the foot.
Is lower drop better for forefoot running?
Some runners who naturally land farther forward enjoy lower-drop shoes, but foot strike alone should not dictate your shoe choice. Comfort, previous footwear and the overall design of the shoe are also important.
Does higher drop protect your Achilles?
A higher drop can change the mechanical demands around the ankle and Achilles compared with lower-drop footwear. But that does not make a higher-drop shoe a guaranteed solution for Achilles problems, and footwear should not replace appropriate medical or rehabilitation advice if you are injured.
Can changing shoe drop cause soreness?
It can. A noticeable change in footwear can alter which tissues are being asked to do more work. That is why a gradual transition is sensible, particularly when moving substantially towards lower or zero drop.
Should beginners worry about shoe drop?
Usually, not too much. If you are buying your first proper running shoe, focus first on fit, comfort, intended use and how the shoe feels when you run. Drop is useful information, but it should not make choosing your first shoe unnecessarily complicated.
The number matters. Just not as much as you might think.
Heel-to-toe drop is worth understanding. It helps explain why two shoes can feel different, and it becomes particularly relevant when you are moving significantly away from the type of shoe your body is accustomed to.
A 4 mm shoe is not automatically better than an 8 mm shoe. Zero drop is not a badge of better running form. And a higher-drop shoe is not an inferior or old-fashioned choice.
The right question remains the same one we use across Xciter: does this shoe make sense for you, the way you run and what you are trying to do?
Because understanding the numbers should make choosing your running shoes easier. Not more complicated.
Explore our Road Running Shoes or speak to the Xciter team if you would like help comparing your options.