When do your running shoes actually die?
“300 to 500 miles” is the same line every brand publishes, for every shoe they make. It is not useful. What decides when a midsole is dead is the foam it was moulded from — and that is knowable.
Which foam is in your shoe?
Brands almost never say “PEBA”. They say ZoomX, or FuelCell, or PWRRUN PB — all of which are PEBA. Here is the translation for the foams you are most likely to be standing in.
| You'll see it called | It is | Road life |
|---|---|---|
| Enerzy, CMEVA, and most GT/Wave trainers | EVA | ~800 km |
| DNA Loft v3, FF Blast+, Nitro, Fresh Foam X, Helion HF | Supercritical EVA | ~700 km |
| Boost, Powerrun+ | TPU | ~800 km |
| Lightstrike Pro, IncrediLux | TPEE | ~650 km |
| ZoomX, FuelCell, PWRRUN PB, FF Turbo | PEBA | ~500 km |
| Vaporfly, Metaspeed, Adios Pro, Endorphin Pro | Race PEBA | ~320 km |
| Adios Pro Evo, Metaspeed Ray, Endorphin Elite | Ultralight race foam | ~240 km |
What “worn out” actually means
Not the outsole, and not the upper. Both of those usually outlast the part that matters. What wears out is compression set: the midsole foam permanently flattens under repeated load and stops returning the energy it used to. The shoe still looks fine. It just stops doing its job.
This is why mileage is a better guide than appearance, and why the number differs so much between shoes. A racing foam is a consumable. A TPU trainer very nearly is not.
The signs, in rough order of arrival
- The shoe feels flat — harsh on landing, dead on toe-off.
- Creases across the midsole that stay put when you press them out.
- Aches that arrive with a particular pair and go away with another.
- Outsole rubber gone through to the foam under the forefoot or heel.
Rotating pairs genuinely extends life
Foam recovers between runs, and giving it 48 hours rather than 24 lets more of that recovery happen. Two pairs alternated do not last twice as long as one pair — but they last meaningfully longer than half each, and the variation in load is easier on your legs.
Why there is no official number
We looked. No brand publishes a per-model mileage figure. Nike, Brooks, Salomon and Hoka all publish the same category-wide line and nothing model-specific, and there is no catalogue or API that carries one. So the honest approach is to store what a shoe is made of — a fact — and keep the mapping from foam to kilometres as a policy in one place, which is exactly what the Outrunr app does.
Common questions
Why not just use 500 km for everything?
Because it is wrong in both directions. A Hoka Bondi outlives it by around 300 km and an Adidas Adios Pro Evo is finished less than half way there. The flat figure also has an awkward origin: it is the low end of the industry's “300–500 miles”, quoted in miles and then widely read as kilometres.
Why does the foam matter more than the brand?
Compression set — how much a foam permanently flattens under repeated load — clusters tightly by chemistry. Traditional EVA compresses slowly and predictably. PEBA is the lightest and springiest and dies first. Two shoes from different brands using the same foam family behave far more alike than two shoes from the same brand using different foams.
How do I find out what foam my shoe uses?
The table further down names the common marketing foams and what they actually are. Brands rarely say “PEBA” — they say ZoomX, FuelCell, PWRRUN PB or FF Turbo, which are all PEBA.
Why are racing shoes capped lower?
A plated super shoe cannot outlive the bond between its plate and its foam, whatever the midsole is made of. That is why the racing figure is capped regardless of how durable the foam family would otherwise be.
Why do trail shoes get treated differently?
Trail life is decided by the outsole, not the midsole. Lugs round off and stop gripping while the foam still has bounce left, and rock plates shield the foam from the worst of the impacts. So trail shoes lose a little to the tread and get a ceiling of their own.
Is the number a hard deadline?
No. It is the point at which the cushioning has measurably changed, not the point at which the shoe falls apart. Many runners demote a pair to easy runs and walking rather than binning it. What you should not do is keep racing in it.
More free tools
Stop guessing at the shoe rotation.
Outrunr tracks each pair as you run, weights every kilometre by surface and effort, and tells you when a shoe is done — before your knees do.