When Should You Replace Your Running Shoes?

Running shoes wear out. The midsole foam compresses over time and loses its ability to absorb impact, long before the upper shows any visible damage. Most runners keep shoes too long — and worn-out shoes are one of the most common causes of overuse injuries like shin splints, knee pain, and plantar fasciitis.

The 500 to 800 kilometre rule

The general guideline for replacing running shoes is every 500 to 800 kilometres, or roughly 300 to 500 miles. The range is broad because it depends on several factors: your weight, your running surface, your gait, and the specific shoe model.

Heavier runners and those who run primarily on hard surfaces tend to be at the lower end of this range. Lighter runners on softer surfaces may get closer to 800 kilometres. Carbon plate racing shoes wear faster than standard trainers — expect 300 to 500 kilometres from a race shoe before the foam loses its responsiveness.

Signs your shoes need replacing

The midsole is the most important part to monitor. Press your thumb into the midsole: a fresh shoe will spring back immediately. In a worn shoe the foam feels dense and compressed and does not return to shape as quickly. This is the primary indicator that protection is compromised.

Worn-down outsole rubber is the most visible sign but it is often a lagging indicator — the foam underneath degrades before the rubber shows obvious wear. Check the heel and forefoot of the outsole for any area that has worn through to the midsole material, which appears as a different colour or texture.

If you start to develop aches or soreness in your shins, knees, or hips that were not there previously, and your training has not changed, old shoes are often the culprit. The body adapts to the cushioning gradually as it degrades, which means the change is subtle until it is not.

How to track your mileage

The simplest way to track shoe mileage is to log it in whatever app you use for running. Strava allows you to assign shoes to individual runs and tracks the cumulative distance automatically. Garmin Connect offers a similar feature. Setting a reminder at 600 kilometres gives you time to find and break in a replacement before the old pair is fully done.

If you do not use a GPS watch, keep a note of when you bought the shoes and roughly how far you run per week. A runner covering 40 kilometres per week will need a new pair every 12 to 20 weeks.

Rotating between two pairs

Many regular runners use two pairs and rotate between them. This extends the life of both shoes significantly — foam recovers better between runs when it has 48 hours to decompress rather than being compressed again the next day. It also means you always have a backup if one pair gets wet.

The rotation does not need to be different types of shoe. Two identical pairs of your favourite daily trainer, offset by a few months of purchase, means you always have one fresher pair available for long runs and one slightly more worn pair for easy days.

Finding your replacement

When your current shoes are approaching their end, use RunSizer to find the best price on your replacement across UK retailers. If you are happy in your current model, buy the same shoe again — consistency reduces the chance of adjustment-related niggles. If you want to try something new, compare what is in stock in your size before making a decision.