Is Wearing Shoes a Half Size Too Big Bad for Your Feet? The Science, Risks & Real-Life Advice

You pull on fresh kicks and wiggle your toes. There’s a surprising bit of extra space up front. Maybe you bought them because your size was out of stock, or your feet swell after a long day. Here’s the thing: tons of people wear shoes that aren’t quite the right size—and most commonly, those shoes are a little too big. It’s easy to assume a half size up won’t matter, but is that true? Or are you sabotaging your feet in the hopes of comfort?

What Happens When You Wear Shoes That Are Too Big?

This isn’t just about style. Your feet are complex machines packed with 26 bones, more than a hundred muscles, tendons, ligaments, and endless sensors all working overtime to keep you balanced and moving. So what really happens when your shoe is about 4 to 5 millimeters longer than ideal?

Let’s start with what the experts say. Podiatrists in Canada and the U.S. agree: sizing up by half can seem harmless, but your foot won’t sit as snug as it should. That gap doesn’t just leave you feeling like you’re wearing a clown costume; it throws off your biomechanics. Your heel might slip, forcing your toes to grip and flex just to keep the shoe on while you walk. Over time, that can cause some gnarly side effects—think blisters, calluses, and sometimes nasty corns. Not fun when you’re just trying to get through the workday or crush a 10k in Prince’s Island Park.

And here’s a bit of a shocker: a 2022 study by the Footwear Research Institute analyzed more than 2,000 adults and found that around 63% of people wear shoes that are the wrong size. The researchers linked even a half-size misfit to some specific problems. Here’s what people reported most often:

So, it’s not just a comfort issue. Shoes that are too big mess with your posture and your stride, raising your risk for tripping and missteps. Even just scuffing your toes a few extra times a day makes you more likely to stub or injure them, especially on uneven sidewalks in Calgary winters. Plus, if your foot slides forward, you can develop black toenails (especially common in runners) or add unwanted pressure to your toes and joints.

Interestingly, this misfit can also add stress higher up your body. When your base is unstable, your knees, hips, and back start overcompensating. People with chronic pain often discover their shoes are a hidden culprit. And it might sound wild, but wearing a shoe that flexes at the wrong spot can lead to plantar fasciitis—an injury that’s basically public enemy number one for runners and anyone on their feet for hours.

How about arch support? In shoes that fit too loose, your arch slides with every step and doesn’t get the support it should. This lack of support slowly wears out your plantar fascia (the thick band at the bottom of your foot), straining muscles and ligaments, which makes you more likely to feel tired and sore even if you haven’t moved much.

Some people swear by bigger shoes because they feel less constricted—especially those who deal with bunions or wide feet. But that loose fit can lead to friction hotspots in brand-new places. And if you’re wearing the wrong socks, the combo of bunching and excess space can make things ten times worse.

On the flip side, there are times when a little room is actually recommended. Athletes like long-distance runners sometimes choose a half-size bigger to accommodate foot swelling over the duration of a race. That’s about the only scenario where experts give it the green light—but only if the shoe still supports your heel and midfoot without sliding.

Why Do So Many People Buy Shoes That Are Too Big?

If you ask around, you’ll hear all kinds of reasons why someone might buy a bigger size. The classic ones? Their “usual” size was sold out, or both feet aren’t quite the same—most people have one foot a little longer. Some folks just like having ‘room to grow’, like when buying for kids, and others think a looser fit is always comfier. In Canada, shoe stores often run out of average sizes, so choosing a half size up feels easier than dealing with cramped toes.

Let’s talk numbers. Multiple surveys, like one done by the Canadian Podiatric Medical Association in 2023, found almost 2 out of 3 people are wearing shoes that don’t accurately fit their dimensions. For most, it’s shoes that are too big, not small. Weirdly, a lot of people measure their feet wrong. Feet can swell a bit at the end of the day, and many people only try on one shoe. A good 30% of people actually buy shoes for their smaller foot, leaving the bigger one to “float” inside extra space.

Fashion plays a sneaky role too. Chunky sneakers and casual boots look great oversized on social media, and some brands’ fits are notoriously all over the map. If you shop online, trying to guess the best size without testing them on carpet at the store becomes a full-on gamble. Half of us think a small heel slip will break in eventually—but the reality is, shoes don’t shrink with time.

And then there’s the myth that feet stop changing after your late teens. Not true. Pregnancy, injuries, aging, and even weight gain or loss can all change your foot size by a half or even full size, particularly in adulthood. That means the number printed on a box when you were in college might not apply ten years down the road. Plus, in the dead of the Canadian winter (yep, even those minus-30 days in Calgary), some slip boots a size up just to fit thick socks. That could spell cozy disaster for your foot health if it becomes your daily habit.

I’ve chatted with shoe pros in downtown Calgary who say they see it every week: people come in assuming they need one size, only to walk out with a proper measurement that surprises them. Some spend years thinking they’re a 10 when they’re really a 9 or even 8.5, and they’re shocked when their foot pain disappears with a proper fit.

Children’s shoes are a whole different animal. Parents in Canada frequently buy shoes “a bit big” so their kids can wear them longer. It saves money, but growing feet in loose shoes tend to develop issues like uneven gait and risk rolled ankles—sometimes setting up foot problems that last into adulthood.

If you’re in a hurry or shopping alone, you might skip the key steps: standing up while fitting (because feet get longer when they’re bearing weight), testing with your everyday socks, and making sure there’s about a thumb-width at the front—not a full inch. Even running brands have slightly different ideas about what, say, “size 9” really means.

Expert Tips: How to Pick the Right Shoe Size and Fix the Problem

If your shoes feel off, here’s good news: you don’t have to choose between pain and a little extra toe wiggle room. Start by measuring both feet at the end of the day, when they’re at their biggest. Wear your normal socks. Stand up—don’t sit. Shoe pros use a Brannock device for a reason: it’s the gold standard for accuracy, even if it looks a little retro (and if you’re buying in-store in Calgary, good shops like Gravity Pope or The Shoe Company still have one).

• Aim for about a centimeter (or roughly the width of your thumbnail) between your longest toe and the shoe tip. Not more.
• The ball of your foot should sit at the widest part of the shoe. That’s where your foot bends naturally—which matters a lot for walking and running.
• If your heel is slipping, try a heel grip pad or lacing technique before assuming you need a bigger or smaller size.
• Trust your body more than the number. If your toes splay or curl when you walk, your shoe is probably too big or too small, even if it says “your size.”
• If your shoes are already too big but you can’t return them, insoles and thicker socks can help, but these are band-aids, not cures. Don’t rely on this long-term, especially if you walk or run a lot.
• Look for shoes marked with “wide” rather than sizing up for width. This keeps length right while easing pressure elsewhere.

Here’s something most people miss: your feet flatten and spread as you get older. If last year’s size feels roomy, it’s worth being remeasured. Pregnant? Your arches might not bounce back to pre-baby size. Adding sports, working long shifts, or recovering from injuries? Your shoe requirements will shift too.

In sports, a bit of leeway is sometimes fine—runners and hikers may opt for a plus-half size, but only if heel slippage isn’t an issue and you’re not compensating anywhere else. Some experts suggest if you must size up, pick a shoe with extra eyelets for lacing lock-down. Track athletes here in Calgary often ask about race day swelling. Local coach Jordan Miller recommends testing your shoes in the afternoon—feet can be up to 5% larger than first thing in the morning, so playing it safe for long events means more accuracy when you truly need it.

Remember, even luxury brands don’t guarantee perfect sizing. Don’t trust only size charts—everyone’s foot shape is unique, so two people with the same shoe size can need totally different fits. Arch height, toe shape, and even your personal walking style play into what works best.

Paying attention to fit today saves a pile of issues down the line. Foot pain and posture problems don’t just ruin your day—they snowball into bigger problems that can be tough to reverse. If you’re not sure what “just right” feels like, pop into a reputable store and get fitted. It’s worth it, trust me.

Shoes aren’t meant to punish you or make you work harder just to keep them on. They should support and move with you, not against you. That half size might not seem like much at checkout, but day after day, your feet will let you know if you made the wrong call.