How Long Do Running Shoes Last? 3 Theories On When to Replace

As with all things in life, there are differing opinions on how long you should keep a pair of running shoes in your rotation (surprising, huh?). At a high level, there are two camps on the issue: one side that says replace 'em once they start to get worn out, whether that's monitored by mileage, time or a visual check, and another side that says it's okay to run in your trainers until they don't function anymore. 

If you're here, it's likely you're in the former camp (as are we) and want to replace your shoes before they're torn threadbare. Below, we've broken out some common sense ways to tell when it's time to retire your trusty trainers.

When To Replace Running Shoes: 3 Theories

If you're looking for an excuse to buy a new pair of trainers, or if you're looking for confirmation that you can rock with your current a bit longer, there's an expert somewhere that agrees with you. Here are the three most common ways to tell that it's time to replace your shoes.

1. Mileage Theory: 300 to 500 Miles

The mileage theory is the predominant way that runners decide how long to keep their shoes. This theory suggests that running shoes have a certain usable life, which is measured in miles, after which they should be replaced. The target for most runners is 300 to 500 miles (480 to 800 kilometers) of use, though some athletes take their shoes to 700+ miles—I once got 770 miles from a pair of Adidas Ultraboost. 

The mileage theory assumes that the cushioning and support in shoes gradually deteriorates with mileage run, potentially leading to a higher risk of injuries over time. This means that a shoe can still look brand new, especially if you're done mostly dry weather or treadmill running in a pair, but will need to be replaced regardless.

If you're interested in using this method, there are some low lift ways to monitor a shoe's mileage. With apps like Strava and Nike Run Club, you can upload all of your running shoes and assign them to runs that you log in the app. With Strava, you can even set mileage alerts and get a notification when you've hit your mileage target for a pair of shoes.

Use this if: You rotate your shoes and don't mind tracking mileage.

2. Time-Based Theory: 6 Months to 1 Year

The easiest way of knowing when to replace your shoes is the time-based theory, also known as the calendar method. According to this theory, running shoes should be replaced after a certain amount of time, regardless of mileage. The rationale behind this theory is that the materials of the shoes, including the midsole and outsole, can degrade over time, affecting their performance and support. Because of this, it's a good idea to rotate your shoes, as it can extend the life of the foam (plus it will minimize injury risk and vary the muscles engaged while running).

For most runners who hit the roads a few times per week, this will add up to a few hundred miles over the course of the time period. If you tend to run a consistent weekly mileage number and do this all in one pair of daily trainers, you can do a simple upfront calculation to predict how long it will take to hit 300 to 400 miles (this is a subtly disguised use of the mileage theory)—for example, with three runs of five miles a week, you'll hit 400 miles in roughly six months (Editor's note: With calculations like 3 runs * 5 miles * 26 weeks = 390 miles, it's clear I'm putting my MBA to good use.).

Use this if: You have one pair of shoes or can't be bothered to track mileage.

3. Wear and Tear Theory: Midsole Compression, Outsole Damage

This theory focuses on the physical condition of the shoes. It suggests that your shoes should be replaced when you can see damage. Common signs are worn-out outsoles that expose the rubber, excessively creased midsole foam or torn uppers. New shoes can be expensive, so if you're trying to keep your shoes costs affordable, then this is a good method to consider—as you may get more life out of your shoes this way, especially if you take care of them, keep them clean and only run on the terrain for which they were designed.

While it's a good idea to monitor your shoes for damage, appearance doesn't always translate into performance—dirty shoes can still perform well, while shoes that have no signs of wear (maybe they've been run exclusively on the treadmill) may have cushioning that's lost its pop. Particularly for the midsole, visual signs of wear can differ a lot based on the type of foam used in a shoe's midsole, as some like EVA more resilient than others. 

Of the three methods, this is the riskiest, as you might not catch a shoe's inefficacy until it's hampering you on a run, which could lead to an injury. As such, it's a good practice to have a rough idea of how much mileage you've run or how long you've owned a pair of shoes as a second way to check if you should keep running in a pair. 

Use this if: You're on a budget and do not have an injury history.

The Best Way to Know When It's Time to Replace Your Shoes

We've come full circle here—because as with all things in life, the best answer comes from a combination of perspectives. Mileage, time and visual checks can be combined to help you decide when it's time to retire your trainers. Not all shoes will show signs of damage when they're ready to be replaced, so if you can stomach adding another step to your running routine, it's a good idea to start tracking mileage.

And why is this important? Because monitoring the condition of your shoes regularly and replacing them when they show significant wear or reach mileage targets can help prevent potential injuries, keeping you injury-free and ready to smash your next PR.

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