When it comes to trail running, finding the right shoe size is beyond important! So, while you could probably make do with a size smaller or bigger when you’re just walking around, as a set of daily wear shoes, trail running is a whole other can of worms. With that in mind, quite a few trail runners normally wonder about the same thing… “Should I buy trail running shoes a size bigger?”
It’s not weird to consider a size bigger for trail running, because unlike regular running shoes, trail running shoes need to accommodate swelling, rough terrain, as well as running very long distances. To answer this, let’s take a closer look at why size matters when you’re shopping for a new set of trail running shoes, as well as some of the benefits of upsizing, and a few tips that I could offer you on finding the perfect fit!
Why Does Size Matter In Trail Running Shoes?
Size matters in trail running shoes because it can account for your foot swelling during runs. Let’s take a deeper look:
- During long runs, your feet will naturally swell due to increased blood flow and impact as you run harsh, arduous trails.
- Additionally, when you’re trail running, you’ll experience more swelling than road runners due to the uneven terrain that you’ll come across, as well as way more time spent on your feet.
- Consequently, a tight-fitting trail running shoe could easily cause you discomfort, pain, or even injuries!
Otherwise, wearing a correctly sized pair of trail running shoes should also help you out with preventing common injuries:
- Trail running shoes that are too small can lead to painful black toenails, which happens when you put a lot of repeated pressure on your toes.
- Moreover, blisters and hot spots can happen commonly enough when your trail running shoes don’t allow enough room for your foot’s expansion.
- Aside from that, trail runners with a snug fit in their shoes often develop toe cramping or even Metatarsalgia, which is a painful inflammation in the ball of the foot.
It does depend on how far of a distance you’re running though. If you’re training for a marathon, the size of your trail running shoe does really matter. But if you’re very much a beginner at running and are perhaps training for a couch to 10K, or you’re not really covering the longer miles, you might not get as much swelling. And to add to that again, if you’re completely new to exercise, and aren’t used to the movement as much, your feet may swell a little more.
It’s a bit like when I used to go on day long shopping trips with my mum! We’d never go shoe shopping at the end because your feet swell and it’s not a true reflection of the size you actually need.
What are The Benefits Of Upsizing Your Trail Shoes?
So, should you buy trail running shoes a size bigger? Well, it turns out that it might be a good idea after all, on account of the many advantages that you could experience when you choose to upsize your trail running shoes. Here’s 3 benefits:
1. Increased Comfort During Longer Runs
A slightly bigger shoe size (I’d often suggest a half or full size bigger) should allow for some adequate swelling with your foot without constricting your foot. Additionally, it ought to help you with reducing your pressure points, which could make longer runs more enjoyable.
2. Better Protection On Rough Terrain
A looser toe box should aid in preventing your toes from constantly hitting the front of the shoe. This isn’t just painful and discomforting, but it would also help out a lot when you’re running downhill. In addition, more room would also prevent any rubbing and irritation when you’re running on steep inclines or rocky trails.
3. Reduced Risk Of Injury
With proper space in (upsized) your trail running shoes, you can do a ton while minimizing the risk of hammer toes, ingrown toenails, and nerve compression. All of those are the usual injuries that are common with tight-fitting shoes. Plus, shoes that are too tight can and will restrict your blood circulation, leading to numbness or tingling during runs.
How Does Shoe Fit Affect Trail Running Performance?
Aside from injuries and comfort, should you buy trail running shoes that are a size bigger, you might also experience improved performance, too! So, for all you competitive trail runners out there, here’s 3 ways in which proper shoe sizing could maximize your trail running experience:
1. Stability & Control As You Run
Although upsizing can be beneficial, you’d have to be careful not to go too far! So, bear in mind that trail running shoes that are too big can cause heel slippage, reducing your control on some of the more technical, challenging trails.
2. Energy Efficiency
When you’re trail running, to most optimal way to do it is to rely heavily on efficient energy transfer, from foot strike to push-off. Alternatively, shoes that are too tight or too loose could force your foot to work even harder than necessary, leading to faster fatigue.
3. Ground Feel vs. Protection
Meanwhile, some trail runners prefer a more snug fit that offers a better ground feel and responsiveness. However, other trail runners might prefer their shoes a bit more on the roomier side, offering better comfort or protection over rough ground.
You’ll figure this out yourself when you start running more on trail routes. More on that later..
Should I Buy Trail Running Shoes A Size Bigger? Fit Issues And Solutions
If you’re having trouble with the size of your trail running shoes, here are some things that I’d recommend that could help:
- Heel Slippage – If upsizing your trail running shoes causes excessive heel movements, you could try the heel lock lacing technique to secure your fit. Alternatively, you could try using a slightly thicker sock, which ought to help minimize unwanted movement.
- Toe Box Space – Experts generally recommend at least a thumb’s width between your longest toe, and the front of the shoe. As such, if your toes hit the front of your shoes during downhill runs, you should consider upsizing.
- Midfoot Tightness – You’ll also find that a wider or more flexible shoe can accommodate some broader foot sizes without requiring a larger shoe size. Otherwise, if the midfoot feels too snug, you should look for shoes with an adjustable lacing system.
My Tips On Choosing The Right Size of Trail Shoes
If you’re still wondering about whether or not you should buy trail running shoes a size bigger, here are some expert tips that could help you decide:
- Measure Your Feet Properly – You should try to measure your feet in the evening or after a run to account for the swelling that you experience during trail running. Ideally, you should stand while measuring to ensure a more natural weight-bearing position.
- Wear The Right Socks – Remember to try on trail running shoes with the same socks that you’ll wear on the trail. You should also consider wearing moisture-wicking, cushioned socks that will add a bit of extra comfort.
- Check For Width And Volume – Bear in mind that shoe size isn’t just about length! Other factors such as width and volume also matter. When you’re shopping for a new set of shoes, there are brands that offer wide versions of their trail running shoes, which might offer a better fit.
- Test Shoes On An Incline – When you’re trying on new trail running shoes, try walking or even jogging on an incline to see if your toes hit the front. While you’re doing that, make sure that your heels stay secure, without excessive slipping.
Adjusting To A Larger Shoe Size
I know that it’s not easy or comfortable (at first, anyway) to adjust yourself to a slightly bigger shoe size than what you’d normally wear, so here are some hacks that I’d recommend:
- First up, try breaking your new trail running shoes in gradually. In other words, even if a shoe feels comfortable, gradually break it in before taking it out on long runs. You could do this by starting out with short walks or easy runs first to ensure that they fit your feet right.
- And, if that doesn’t help, or if a shoe feels too roomy, you could try adding an insole to your running shoes. They can help out with adjusting the shoe’s inner volume and even provide better arch support! I know some trail runners also prefer wearing custom orthotics for that extra comfort.
- Another neat trick I’ve learned is by experimenting with lacing techniques. The runner’s loop or parallel lacing could help with tightening specific areas without causing discomfort. You could also adjust your laces accordingly, preventing slippage and improving foot lockdown.
How Do I Know If Trail Running Shoes are Right for me at all?
There’s so many types of running shoes out there and if you’re an experienced runner, it’s a bit easier to know what fit you like. But if you’re slightly newer, it can be harder because you don’t know what you don’t know, like anything! But don’t worry. You’ll work out what you like as you run more often and run on different terrains because trail running is very different to road running – some runners really have a preference!
How do I know if I’m a trail runner?
It really depends what you’re used to and where you live. For example, when I started running I lived in the city and so road running was more of a thing for me just because of my location! There was a very small lake I used to run to, run around and then run home. So that lake was about the only ‘trail’ route I’d do, and it was about 10% of my actual run. The rest being road. But I since moved to a more rural area and so I have easy access to a very well known trail route in the Peak Distract in the UK, so naturally I run on the trail a lot more.
It’s funny looking back. When I first started running years ago, you’d have called me a ‘road runner’ not a trail runner. And I wouldn’t have even known what a trail runner was. So I completely understand that there’s quite a bit of jargon around running and if you’re a beginner, you might not know what running shoes you need at all!
Should I Buy Trail Running Shoes A Size Bigger: Key Takeaways
If you’re totally new to running right now, and you haven’t figured out what terrains (road, trail, etc) is near you and you actually enjoy running on, any affordable running shoes will do to be honest (see some of my product reviews at the end of this guide if you need some inspo). But if you’ve been noticing that you are running on trails more, then it’s absolutely worth working out what kind of feel you prefer.
So, in summary… A half-size up is usually enough for most trail runners. If not, going too large could massively reduce stability, so while I’d highly recommend that you consider upsizing, it’s bad to go too far! Your fit should be snug in the midfoot while allowing some toe room. If you experience black toenails, pain, discomfort, or excessive rubbing, then you will know that your shoes might be too small.
On the flip side, if your foot moves around too much inside the shoe, consider adjusting socks, insoles, or your lacing. Experimenting through trial and error works too, as some runners like that snug fit, while others need more room. I always recommend folks choose a size that best suits their running style. While you’re at it, try out and test different brands and models, since sizing and fitment could vary!
Need running shoe inspiration?
I’ve worn a couple of running shoes in my time (and so has my dad who got me into it!) and so I feel well equipped to provide you with a couple of reviews:
Written by Katie McDonald, Friday 24th January 2025.
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