Running Shoe Specs Explained

What does a 10 mm drop actually change, and is a carbon plate really an upgrade? Shoe listings are full of numbers that sound precise and are rarely explained.

Here is what each one means — and, more usefully, what range it actually falls in, measured across the 305 fully-specced shoes in the ATHLO+ Shoe Lab.

Heel-to-Toe Drop: Where the Load Goes

Drop is the difference in foam thickness between your heel and your forefoot. A 10 mm drop means your heel sits 10 mm higher. It changes where load is distributed, not how much of it there is. Roughly speaking:

• Higher Drop: Shifts work away from your calf and Achilles and towards your knee.
• Lower Drop: Does the reverse.

In this dataset drop runs from 0 mm to 12 mm, and 8 mm is the median. 9 shoes are zero-drop and 56 sit below 6 mm, so the low-drop end is a real minority.

There is no correct number. What is worth avoiding is switching abruptly between very different drops, not any particular value.

Stack Height: How Much Foam Is Under You

Stack is how much foam is underfoot, quoted at the heel and the forefoot. Heel stack here runs from 18 mm to 55.5 mm — the tallest being the Nike Vomero Premium at 55.5 mm.

The 40 mm Rule: World Athletics caps stack height at 40 mm for road racing. A shoe above that is not race-legal for a ranked road result, which is why the very tallest shoes are marketed as trainers.

Plates: A Different Tool, Not an Upgrade

A plate is a stiff insert in the midsole. It does not generate energy. It stiffens the shoe so that a thick, soft foam can be used without the whole thing collapsing sideways, and it stops your toe joint bending as much as it otherwise would.

Of these 305 shoes, 80 use carbon and 187 have no plate at all. The rest use nylon, Pebax, rods or a proprietary variant, which are progressively more flexible. A stiff racing plate under easy mileage is not doing you any favours.

Foam: The Names Are Marketing, the Chemistry Is Not

The midsole compound is where brands compete hardest on naming. Broadly:

• PEBA-Based Foams: Lighter, and return more energy than EVA-based ones.
• Supercritical Foams: Nitrogen-injected, and sit between the two.

The lightest shoe in the Lab, the Adidas Adizero Adios Pro Evo 3 at 97 g, is a good illustration of what modern foam plus a minimal upper gets you.

Weight: The Most Over-Weighted Number

It is the most obvious figure, and the one people read too much into. It is quoted at a single sample size, usually a men's US9, so your pair will differ. A 30 g difference is noticeable; a 10 g difference is mostly a spec-sheet argument.

Compare by Category

• Carbon plate racing shoes
• Super trainers
• Daily trainers
• Max cushion shoes
• Stability shoes
• Trail shoes

Compare by Brand

• Asics — 33 models
• Hoka — 31 models
• Nike — 27 models
• Saucony — 26 models
• Adidas — 24 models
• Brooks — 24 models
• On — 22 models
• New Balance — 21 models
• Puma — 17 models
• Mizuno — 15 models

Want to put two shoes head to head? The ATHLO+ Shoe Lab stacks any two to four of them against each other on the same specs.

Find Your Fit with FORGED by ReFormd on ATHLO+

A spec table can narrow the shelf, but it cannot watch you run. FORGED by ReFormd's 3D running gait analysis, which you can book on ATHLO+, comes with a shoe recommendation.

Book 3D Running Gait Analysis with FORGED by ReFormd on ATHLO+ →

Ready to see how your own stride puts all of this to work? Read our guide to running gait analysis next.

Where these numbers come from

Manufacturer-published specifications compiled in the ATHLO+ Shoe Lab, powered by iRUN Singapore. These are specs, not our own test results, and nothing here is ranked or recommended. Figures are quoted at the maker's sample size and vary with yours.