You're standing in the middle of a crowded sneaker shop, eyeing a pair of limited-edition Dunks that only seem to exist on the "men’s" wall. You're a women’s size 9. You look at the box, then at your feet, then at the salesperson who looks equally confused. Honestly, it’s a mess. Most people think they can just subtract two and call it a day. They’re wrong. Women’s size 9 is what in men’s? It’s a 7.5. Usually. But if you stop there, you’re probably going to end up with blisters or a heel that slips every time you take a step.
Sizing isn’t just about length. It’s about volume.
Why the 1.5 Rule Isn't Actually a Rule
Most major brands like Nike, Adidas, and New Balance tell you that the standard conversion is a 1.5-size difference. If you wear a women's 9, you grab a men's 7.5. Simple, right? Well, sort of. This math assumes that feet are two-dimensional objects. They aren't. Men’s shoes are built on a different "last"—that’s the mechanical form shaped like a human foot that shoemakers use to build the shoe.
A men’s 7.5 is almost always wider than a women’s 9. Specifically, a standard women’s shoe is a "B" width, while a standard men’s shoe is a "D" width. That’s a significant jump. If you have a narrow foot, that 1.5-size drop is going to feel like you’re wearing a pair of shoeboxes. You’ll have all this "dead space" around your midfoot. On the flip side, if you’ve always struggled with women’s shoes being too tight, moving to a men’s size 7.5 might be the best thing you’ve ever done for your bunions.
The Brand Variance Headache
Don't even get me started on how brands refuse to talk to each other. A size 9 in a Steve Madden heel is not a size 9 in a Brooks running shoe.
📖 Related: Is there actually a legal age to stay home alone? What parents need to know
Take Converse, for example. They’ve basically abandoned the gender binary in their sizing for the Chuck Taylor All Star. Look at the bottom of a pair of Chucks. You’ll see two numbers. For a women’s 9, you’re looking at a men’s 7. It’s a two-size difference there, not 1.5. Why? Because Converse runs large and they use their own internal logic that seems to date back to the early 20th century.
Then you have the European brands. Birkenstock or Ecco? They use centimeters and European sizing (like 40 or 41). In those brands, the concept of "men’s vs. women’s" often disappears entirely because a 40 is a 40. If you’re a women’s size 9, you’re usually a 40 in EU sizing. Whether that 40 is marketed to men or women doesn't change the length of the footbed. It’s a much more honest way to shop, honestly.
Performance vs. Fashion: When the Math Changes
If you’re just buying a pair of Vans to go to the grocery store, a slightly loose fit doesn't matter. But if you’re a runner or a hiker, "women’s size 9 is what in men’s" becomes a safety question.
I’ve talked to podiatrists who see women coming in with black toenails because they switched to men’s shoes for the "cool colorways" but didn't account for the heel cup. Men generally have broader heels. Women’s shoes are often designed with a narrower "Achilles" area to prevent slipping. When a woman wears a men's 7.5, her heel might lift with every stride. That friction leads to blisters. Or worse, it changes your gait and causes shin splints.
👉 See also: The Long Haired Russian Cat Explained: Why the Siberian is Basically a Living Legend
The Q-Angle Factor
There’s also some actual science here regarding the "Q-angle." That’s the angle at which your femur meets your tibia. Because women generally have wider hips, their Q-angle is more pronounced. Many high-end women’s running shoes, like those from Saucony or Brooks, are engineered to support this specific biomechanical alignment. Men’s shoes aren't. A men’s 7.5 is balanced for a straighter leg-to-foot alignment. If you’re a serious athlete, you can’t just swap genders based on a number. You have to consider how the foam is carved.
Real World Examples of the Size 9 Struggle
Let’s look at some specific scenarios. You’re eyeing those Doc Martens. Doc Martens are notorious for being "unisex" but also incredibly inconsistent. For a women’s 9, you’d think a UK 7 (which is roughly a US men’s 8) would work. But Docs run big. Many women find that a men’s 7 actually fits better because the leather stretches so much.
- Nike: Stick to the 1.5 rule. A women's 9 is a men's 7.5.
- Adidas: They often run a bit large; you might actually find a men's 7 fits better if you like a snug feel.
- Vans: They usually list both sizes on the box. It’s a 1.5 difference.
- Luxury Brands (Gucci, Prada): They use Italian sizing. A women’s 9 is a 39 or 39.5. Men’s sizing in these brands often starts at a 40, meaning some women’s size 9s are literally "sized out" of the men’s collection.
The Width Secret Nobody Tells You
Width is the silent killer of shoe comfort. If you are a woman with a wide foot, you shouldn't just look for "wide" women's shoes. You should jump straight to the men's section.
A women’s "Wide" (D) is exactly the same as a men’s "Standard" (D).
✨ Don't miss: Why Every Mom and Daughter Photo You Take Actually Matters
If you go to a department store and ask for a women's 9 Wide, they might have two pairs in the back that look like something your grandma would wear to a physical therapy appointment. But if you walk over to the men's aisle and grab a 7.5, you have the entire wall to choose from. It’s a total life hack for anyone who feels like their toes are being squeezed into a point.
Don't Forget the Socks
It sounds stupid, but socks change the math. Men’s shoes have more internal volume. If you’re wearing thin no-show liners with a men’s 7.5, the shoe is going to feel massive. If you’re going to cross-shop, you need to wear the socks you actually plan on using.
Also, look at the "CM" or "JP" size on the tongue of the shoe. This is the length of the shoe in centimeters or millimeters. This is the only universal truth in footwear. If your favorite women's size 9 says 26cm, look for a men's shoe that also says 26cm. It doesn't matter what the US or UK number says. The metric system doesn't lie.
Practical Steps for Your Next Purchase
Stop guessing. If you're ready to make the jump to the men's section, do it systematically so you don't waste money on returns.
- Measure your foot in centimeters. Do it at the end of the day when your feet are the most swollen.
- Check the "Last." If the shoe is described as "Slim Fit" or "Race Fit," stay with the 1.5 conversion. If it's a "Relaxed" or "Trail" shoe, consider going down a full 2 sizes to account for the extra room.
- Check the return policy. If you're buying men's shoes as a woman, you're 30% more likely to return them due to heel slippage. Only buy from places with a solid "wear and return" policy like REI or Nike.
- Look for "Unisex" labels. These are increasingly common and usually follow the men’s sizing curve but with a slightly narrower heel than a traditional men’s work boot.
- Ignore the labels. Seriously. If the shoe fits, who cares if the box says "Men’s" or "Women’s"? The shoe doesn't know who is wearing it.
The bottom line is that while a women's size 9 is technically a men's 7.5, the physical reality of the shoe's construction might mean you're actually a 7 or even an 8 depending on the brand's heritage and the intended use of the footwear. Check that centimeter measurement on the tag—it is the only way to be 100% sure before you head to the checkout.