You’re staring at your screen, hovering over the "buy" button on a pair of limited-edition kicks. They’re a US 11. You’re in London, or maybe Manchester, and you usually wear a 10. Or is it a 10.5? Buying shoes internationally is a total gamble because, honestly, the math behind footwear sizing is a chaotic mess of medieval history and modern manufacturing quirks.
If you're trying to convert a US 11 to UK size, the short answer is that you usually drop one full size. A US men’s 11 is generally a UK 10. But don't click buy yet. That one-size-down rule is a massive oversimplification that leads to millions of returns every single year.
The "One Size Down" Myth and Why It Fails
Most people think international sizing is a fixed constant. It's not. If you grab a pair of Nike Dunks in a US 11, the box will tell you they are a UK 10. Simple, right? But then you head over to Adidas or New Balance, and suddenly the "standard" starts to wiggle.
The US sizing system is actually based on the length of the "last"—the wooden or plastic foot shape the shoe is built around. A US 11 is roughly 11 inches long, give or take some fractions. The UK system also uses Barleycorns (an ancient unit of measurement equaling 1/3 of an inch), but it starts its counting from a different baseline. Because the US system started later and deviated from the British standard, we ended up with this weird gap where the US number is almost always higher.
But here is where it gets annoying: The Gender Gap.
If you are looking at a US 11 in women's shoes, the conversion isn't a one-point drop. It’s actually closer to two or even two and a half. A US women's 11 is typically a UK 9. If you're a guy buying a "unisex" sneaker that's listed in women's US 11, and you assume it’s a UK 10, you are going to receive a shoe that is painfully small. You've gotta check the CM (centimeters) or JP (Japanese) sizing on the tag if you want the truth. Centimeters don't lie.
Why Brands Can't Agree on a US 11 to UK Conversion
You’d think in 2026 we would have a globalized standard. We don't.
Take Dr. Martens. They are a British brand through and through. Their "standard" fit is notoriously roomy. A US men's 11 in a Doc Marten might feel like a boat compared to a US 11 in a narrow Italian leather dress shoe. Then you have the athletic giants. Nike and Adidas have been fighting a sizing war for decades.
- Nike: Generally follows the "1 size down" rule. A US 11 is a UK 10.
- Adidas: They use third-sizes. You might find a UK 10.5 or a UK 10 2/3. This is because they convert from European (FR) sizing first.
- Puma: Often runs a bit tighter in the midfoot, making that US 11 feel more like a UK 9.5 if you have wide feet.
Manufacturers care more about their specific "last" than they do about international harmony. The last determines the volume of the shoe, not just the length. If you have a high arch or a wide forefoot, the conversion from US 11 to UK becomes less about the number on the box and more about the shape of the brand's DNA.
I've seen people buy a US 11 in a Converse Chuck Taylor—which notoriously runs large—and realize they actually needed a UK 9, a full two sizes down from their US sneaker size. It’s a mess.
The Brannock Device vs. Reality
Remember that silver sliding tool at the shoe store? The Brannock Device. It’s the gold standard for measuring feet, but it measures your foot, not the shoe. A US 11 on a Brannock device is a specific physical length. But once a designer adds padding, a Gore-Tex lining, or a tapered toe box, that "11" doesn't mean what it used to.
Leather also stretches. Synthetic mesh doesn't. If you’re buying a US 11 in a performance running shoe like the Brooks Ghost or Saucony Ride, you need that extra "wiggle room" for foot swelling. In that case, the UK 10 is perfect. But if you’re buying a stiff, heritage leather boot, that same UK 10 might feel like a loose clog after two months of breaking it in.
The Weird History of the Barleycorn
Why is it so confusing? We can blame King Edward II. Back in 1324, he decreed that three grains of barley, dry and round, placed end-to-end, equaled one inch. This became the basis for British shoe sizing.
The UK size 0 was set at 4 inches. Every size up is one "barleycorn" (1/3 of an inch) longer. When the Americans decided to do their own thing, they shifted the starting point. They also decided that women’s sizes should be distinct from men’s sizes, whereas the UK system originally kept them more aligned. This historical divergence is why you’re currently stuck googling whether your US 11 is going to crush your toes or fly off your heel.
Pro Tips for Getting the Right Fit
Don't just trust the chart. Charts are suggestions, not laws.
First, look for the Mondopoint. This is a system used by the military and in ski boots. It measures the foot in millimeters (e.g., 290mm). If you know your foot is 285mm long, look for that number on the internal tongue tag of the shoe. It is the only way to bypass the US vs UK ego battle.
Second, check the "Heel-to-Toe" measurement on the brand’s specific website. A US 11 at Vans is 11.25 inches. At another brand, it might be 11.1. That quarter-inch is the difference between a blister and a perfect day.
Third, consider the socks. If you're buying a US 11 winter boot to wear in the UK, you're probably wearing thick wool socks. That UK 10 conversion might suddenly feel way too tight. Most seasoned hikers actually size up half a size for their UK adventures to account for thick socks and downhill toe-jamming.
Breaking Down the Most Common Conversions
Let's look at how this actually plays out across different categories so you don't get burned.
The Sneakerhead Reality
If you’re buying Jordans or Yeezys, the US 11 to UK conversion is almost always a UK 10. However, Yeezy 350s run incredibly small. Most people in a US 11 actually need to go up to a US 11.5, which would then be a UK 11. If you buy a UK 10 in a Yeezy 350, you're going to have to take the insoles out just to breathe.
Formal Wear and Loafers
Luxury brands like Church’s or Loake use UK sizing as their primary metric. When they export to the US, they often just slap a sticker on the box. A UK 10 in a high-end Oxford is often roomier than a US 11 in a standard dress shoe because they assume a more "generous" fit for gentlemanly comfort.
The Women's Conversion Trap
This is the biggest pain point. A US women’s 11 is a fairly large size in the American market. In the UK, this is a size 9. Some brands will try to tell you it's a UK 8.5. If you see a site claiming a US 11 is a UK 8, run away. They are using an outdated or localized scale that will result in a shoe that’s at least an inch too short.
What to Do if You're Between Sizes
If your foot measures exactly between a US 10.5 and a US 11, you have a choice. In the UK, you’re looking at a 9.5 or a 10.
Always go up. You can add an insole. You can wear thicker socks. You can tighten the laces. But you cannot, under any circumstances, make a shoe longer. Once your toes hit the end of that toe box, the shoe is useless.
Also, pay attention to the width. The US uses letters (D is standard, E is wide). The UK uses letters too, but differently (F is standard, G is wide). If you are a US 11E (Wide), a standard UK 10 (F) will feel like a vice grip. You would actually be better off looking for a UK 10G or even a UK 10.5 to compensate for the lack of width.
Actionable Steps for Your Next Purchase
- Measure your foot in centimeters. Do it in the evening when your feet are at their largest. Use a piece of paper against a wall, mark the tip of your big toe, and measure the distance.
- Ignore the "Main" size. Go straight to the size guide on the specific manufacturer's website and find the CM or MM measurement that matches your foot.
- Check the "True to Size" (TTS) reviews. Use sites like Reddit or specialized shoe forums. Search for "[Brand Name] [Model] True to Size." If everyone says the shoe "runs small," and you are a US 11, don't buy the UK 10. Buy the UK 10.5.
- Verify the return policy. If you are shipping from the US to the UK, or vice versa, return shipping will cost as much as the shoes. If the sizing is a gamble, only buy from retailers with local hubs.
- Look at the tongue tag of your current favorite pair. Check the UK and US sizes listed there. If your most comfortable Nikes are a US 11 and a UK 10, stick with that ratio for other athletic brands.
The transition from a US 11 to UK shoe size doesn't have to be a disaster. Most of the time, the "minus one" rule works. But when it doesn't, it’s usually because of brand-specific quirks or gender-sizing discrepancies. Take thirty seconds to find your measurement in centimeters, and you'll never have to deal with the heartbreak of a beautiful shoe that kills your feet.