One of the best parts about running as a hobby is that it requires so little equipment. you can just walk out the door and run. The only real gear needed is a good pair of shoes, something that will keep your feet from injury.
Shoes of course wear down though, and a worn down pair of shoes can be a recipe for injury.
The life of a running shoe is best measured in miles run, rather than time. For years I ran sporadically, 15-20 miles maximum a week. On a handful of occasions I would train for a race for 3-4 weeks. That totaled 500-1000 miles a year, and ate up a lot of shoes.
How Many Miles Should You Put On Your Running Shoes
Given that experience I can say that on average running shoes lasted a minimum of 350 miles when running primarily trails, and 400-600 primarily use on road runs. This of course can vary widely depending on the surface, your weight, if you run with a hydration pack or added weight, and loads of other factors. Mostly running shoes last until the sole is worn down so much that they provide no grip. In some cases it’s possible to wear a hole in the rubber entirely and then the cushioning breaks down fast!
Running shoes have a life-cycle before they need to be put out to pasture. This is roughly broken into three major phases:
Break In Phase. How Many Miles to Break in Running Shoes?
There are a few reasons to break in a shoe, but mainly it is to avoid injuries (both small and large). Blisters, cuts in weird places, or even full fledged tendonitits are alls possible if running too much in a brand new pair of shoes. Typically swapping shoes in on a full short run is a good idea. If you on average run 3-6 miles a day, then taking them on a 3 mile run is a good idea. There is no good reason to cut a run in half just to break in shoes, but avoiding breaking them in on a long run is a good idea.
Normal Rotation Phase
After breaking them in the shoes wind up being your go-to everyday shoe. This is the primary goal of a running shoe, unless you have specified shoes for different surfaces or paces. It is not uncommon to have a dedicated pair of track or tempo run shoes, and in the normal rotation you should be maximizing the opportunity to use shoes for the right purpose. This should last for 80-90% of the life of the shoe.
Backup Shoe Phase
Typically there is a time where you want to be breaking in a new shoe, but still have old ones. This is the good chance to get some extra life out of shoes. Using running shoes on daily walks, for chores in the yard, or other random uses can extend the life of the shoes. At this point it is fine to not be tracking how many miles you have on the shoes, since they’ll be picking up wear and tear from daily chores.Shoes with a few hundred miles on them, and a worn sole, are still good but it’s important to manage the terrain they are used on. Running a windy uneven path in the rain on old shoes is riskier then running on flat surfaces on a dry day.
For shoes that cause blisters or rubbing, rotating them out of service quicker makes sense. If you are running 50-60 miles a week shoes may last two to three months. If this is the case breaking in a new pair of shoes prior to a big enough is important.
Running a long tempo run? Probably shouldn’t do that in a brand new pair of shoes. That’s how injuries occur. Even if the new kicks are the same model, refreshed.
Below is a picture of a pair of road shoes. One is brand new out of the box, and one has around 300 miles of road and light trails. It’s easy to see where the foot strike is (this is different for every runner).
The soles of shoes will wear down over time and provide support in different areas at the end of their life. Compare the soles of a new pair of shoes with 350+ miles of running to a pair out of the box. The grip of the soles, integrity of the upper, support of the foam will all be effected.
How long shoes last depends a lot on the surface you are running on. It also has much to do with what the shoe is made of. Running on the “wrong” surface for a shoe will wear down its life quickly. How long spiked shoes last is very different if you run across a paved parking lot, especially compared to the soft surface of a good track.
Trail shoes with larger rubber nubs for traction will not only be uncomfortable on hard surfaces, but will also wear down their grip.
For runners who are ramping up the mileage having 5-10 pairs of shoes might be a bit much. But 2-3 pairs of running shoes? That’s reasonable. If you can, never wait until a shoe is totally worn to get and break in a new pair. This will make it easy to avoid breaking in a pair on long runs or races, which is never a good idea.
In my experience all types of shoes last for hundreds of miles, but some may be retired from their specific purpose earlier. Trail shouts last until they turn into road shoes, because they loose the grip that makes them good for soft surfaces. Racing flats are the one type of shoe that last less simply because they often have less material to wear through, but if you save them for races hopefully they last just as long of a time as others.
Seven pairs of running shoes is not too many!
So how is a shoe collection built? One pair at a time of course. But the collection will grow if you pay attention to how long shoes last and run on a variety of surfaces. This is one area where taking the long view and having multiple pairs of shoes many feel more expensive, but ultimately by using a shoe specific to its purpose will justify the added upfront costs.
By tracking how many miles are run on a pair of shoes you can anticipate when they will fail, and plan to break in a pair of shoes at an optimal time during training. Here is a sample list of a modest collection for a running who is training for a moderate of long distance run, anything from 5k and up.
If you are running 35-50 miles a week, it is possible to go through a pair of shoes a month just in simple wear on the sole.
Extending this life can save this monthly costs, since running shoes can easily cost $100 or more. Many runners, myself included, choose to run in the same shoe style year after year to avoid changing something and risking injury.
This list of running shoes to have in the closet (or garage) can help make the weekly mileage more enjoyable:
1. Lightweight track time trial shoes. This is an aspirational shoe. It’s not necessary, but good to strive for.
2. Cushioned, performance enhancing distance running show. If you want a good racing shoe, using it only for a handful of efforts will keep it in top shape. The Nike Tempo has a plate in it that simply can’t last forever. To get the most out of it, keeping it fresh may help get that next % running improvement. 
3. Daily road running shoe. This is a shoe that should last 400-500 miles. I typically try to break them in for 20-30 miles across 4-5 runs before taking them on any long runs.
4. Daily road running, new break ins. This is just a replacement of the above. Once I’ve got a pair of shoes at 250 miles I start to look for a replacement. This make it possible to break in the replacement over time.
5. Daily Trail Shoes. Similar to the daily road shoe, these can last for 300-500 miles. The range is slightly lower simply because of the variety of surfaces encountered. A good run in the snow just can’t be beat, but a newer trail shoe feels totally different than one with 250 miles on it when they touch ice. Where one might be good for winter runs, the worn down shoe might need micro spike attachments to get the same stability as a newer one.
6. Backup Trail Shoe at end of life.
Because they loose their grip, trail shoes are the first ones I move out of a daily rotation. Near the end of life I can get an extra 100 miles out of a trail shoe, but used on trails I know well and where the terrain is easier to navigate. I’ve noticed around 200 mile into a trail shoe I can visibly see the soles wearing and feel them become less stable on questionable surfaces.
7. New Trail Shoe Being broken in.
Having multiple shoes in rotation is practical to avoid having to continuously be breaking in a new pair. It is a luxury to have multiple pairs shoes, but if you can make it work it is easy on your feet. It also lets you extend the life of a worn down shoe that might not be ideal for a hard long run, but which still has plenty of easy pace nice surface runs left.