Women's to men's shoe size conversion: the 1.5 rule and when it fails

Search womens to mens shoe size and every result gives you the same instruction: subtract one and a half. It is a good rule. It is also the reason a lot of people end up with a shoe that is the right length and still wrong.

This guide gives you the conversion table, then spends most of its time on the part that actually causes returns: the four situations where subtracting 1.5 produces a number that fits nobody.

Quick Summary

A women's US size is usually about one and a half sizes above the men's size for the same foot length, so a women's 9 is roughly a men's 7.5. The rule holds for length and ignores everything else, which is why it fails whenever width, volume or the shape of the last is the deciding factor rather than how long your foot is.

• Women's US minus 1.5 equals men's US. That is the whole rule.
• It is a length rule only. It says nothing about width or volume.
• Women's lasts are usually cut narrower, which is the most common reason the conversion disappoints.
• Some brands use 1 or 2 instead, so check before relying on it.
• Unisex sizing removes the problem rather than solving it.

Here is the conversion across the usual range.

Where does the 1.5 rule come from?

It is the residue of two scales that were set separately and never reconciled.

Both US scales descend from the same measuring tradition, where one full size represents about a third of an inch, or roughly 8.5mm of length. The men's and women's scales were simply anchored at different starting points. The gap that resulted happens to work out at about one and a half sizes, which is why the number is so awkward.

That history matters for one practical reason. The offset was never a statement about anatomy. It does not mean women's feet are 1.5 sizes smaller than men's. It means the two rulers start in different places, and the conversion is arithmetic on labels rather than a fact about feet.

Which is exactly why it breaks the moment anything other than length is doing the work.

Failure one: width

This is the big one, and it accounts for most of the disappointment.

Women's footwear is commonly built on a narrower last than men's at the equivalent length. So when you convert a women's 9 to a men's 7.5, you get a shoe that matches your foot for length and is cut wider through the ball of the foot and the heel.

Whether that is good or bad depends entirely on your foot.

• If you have a wider foot, converting into men's sizing often improves the fit noticeably, and plenty of people do it deliberately for that reason.
• If you have a narrow foot, the same conversion gives you a shoe your heel slides around in, and no amount of lacing fully fixes a heel that is too wide.

The length is right in both cases. That is what makes this failure mode confusing: the rule did its job, and the shoe still does not fit. More on how width and length interact is in best minimalist sneakers for wide feet.

Failure two: the brand uses a different offset

There is no standards body enforcing 1.5. It is a convention, and conventions drift.

Some brands use a difference of 1. Some use 2. Some publish no conversion at all and expect you to work from a measurement. A brand that designs primarily in one range and derives the other will often produce an offset that is not 1.5 anywhere in its line.

The practical consequence is that a conversion which worked perfectly with one brand can be half a size out with the next, and you will be tempted to blame your feet rather than the chart. If a brand publishes its own cross range conversion, that figure beats the general rule every time.

Failure three: volume and instep

Length and width are two dimensions. A shoe is a three dimensional object, and the third one has no size number at all.

Volume is how much room there is through the middle of the shoe, over the instep. Men's lasts are generally cut with more of it. If you have a high instep, converting into men's sizing can feel like a relief. If you have a low, flat instep, the same shoe feels loose across the top no matter how tightly you lace it, because you are trying to close a gap that the last built in deliberately.

There is no number on the box for this, which is why it so often gets mistaken for a length problem. The tell is simple: if the shoe feels right at the toes and heel but loose over the top of your foot, that is volume, and resizing will not fix it.

Failure four: the ends of the range

Conversions are tuned to the middle of the scale, where most people are, and they get looser at both extremes.

At the small end, a women's 5 converts to a men's 3.5, which many men's ranges simply do not offer. At the large end, a women's 12 converts to a men's 10.5, which exists easily, but the women's 12 may have been built on a scaled up last that does not match the proportions of a men's 10.5 at all.

Scaling a last up or down is not a simple multiplication. Brands that cover a wide range usually build several lasts and grade between them, so the further you are from the middle of a range, the more the shoe's actual proportions diverge from what the number implies.

Does the rule work in reverse?

Yes, arithmetically. Add one and a half to a men's size to get the women's equivalent, so a men's 9 is roughly a women's 10.5.

The failure modes invert along with it, and this direction is the one people get wrong more often, because it usually comes with an expectation that does not hold.

The recurring surprise in this direction is narrowness. A man converting into women's sizing for a colour or a style that is not offered in his own range gets the right length in a shoe cut noticeably tighter across the ball of the foot, and often finds it unwearable for reasons that have nothing to do with the number.

The second surprise is availability. Women's ranges commonly stop around a US 11 or 12, so conversions above a men's 10 frequently land outside the range altogether.

What about kids and youth sizes?

This is where the 1.5 rule does not apply at all, and treating it as though it does causes some of the worst sizing errors.

Children's sizing is not split by gender, so there is no offset to convert. A youth size is a single number used for everyone. The complication is the boundary with adult sizing rather than the gender split.

Two things to know. First, US youth sizes run up to about 7, and a youth 7 is roughly equivalent to a women's 8.5 and a men's 7. Second, the numbering restarts: children's sizes climb to 13 and then begin again at 1 for youth, which means a youth 1 is a larger shoe than a child's 13. That discontinuity, not the gender conversion, is what causes most mis ordering.

For anyone shopping at the boundary, work in millimetres rather than numbers. A measured foot length is the only figure that stays consistent across children's, youth, women's and men's scales, and it removes every one of these discontinuities at once.

What unisex sizing changes

It removes the conversion rather than improving it.

A single size run used by everyone means there is no offset to apply, no second scale to misremember, and no risk that a brand uses 1 where you assumed 1.5. You are matching a measurement to a number, once.

Atoms is built this way. Model 000 runs from US 3.5 to 15 in quarter increments, as one range, so a 265mm foot orders the same size regardless of which range you would normally shop. The sizing is also finer than either traditional scale, since a quarter size is about 2mm against the 8.5mm of a full size step.

That does not solve width or volume, and it would be dishonest to claim otherwise. What it removes is the translation error, which is the part of the problem that is purely administrative.

How to buy across the two ranges

Six steps that catch almost every cross range mistake.

1. Measure both feet in millimetres, standing, late in the day, and keep the larger number.
2. Find the brand's millimetre column and read from that rather than converting a size you remember.
3. Apply 1.5 only as a starting estimate, and check it against the brand's own chart if one exists.
4. Decide whether you want the width change. Going into men's sizing gives you a wider shoe at the same length, which is a feature or a problem depending on your foot.
5. Check the heel, not the toes, when they arrive. Heel slip is the symptom of a last that is too wide or too voluminous for you.
6. Keep the packaging until you have walked in them indoors for an hour, because cross range fit has a higher error rate than buying within one range.

The arrival checks are covered in more detail in how should sneakers fit. If you are also crossing national systems, the companion guides are UK to US shoe size conversion and EU to US shoe size conversion.

What to do with this

Use 1.5 as a first guess and treat it as exactly that. It is a reliable length conversion and a poor fit prediction, and the difference between those two things is where almost all the returns come from.

If you find yourself converting often, the more durable fix is to stop thinking in sizes at all. Measure once, write the number down, and read every chart from the millimetre column. A measurement does not depend on which range you happen to be shopping, and it does not change when you switch brands.

Frequently asked questions

How do I convert a women's shoe size to a men's?

Subtract one and a half. A women's 9 is roughly a men's 7.5. The rule converts length only and says nothing about width or volume.

Why is the difference 1.5 sizes?

The two US scales descend from the same measuring tradition but were anchored at different starting points, and the gap works out at about one and a half sizes. It is not a statement about anatomy.

Does the 1.5 rule work in reverse?

Yes, arithmetically. Add one and a half to a men's size for the women's equivalent. The usual surprise in that direction is that women's lasts are cut narrower, and that women's ranges often stop around a US 11 or 12.

Why does the conversion sometimes feel wrong?

Because it is a length rule. Women's footwear is commonly built on a narrower last with less volume over the instep, so the converted shoe can be the right length and the wrong shape for your foot.

Is it a good idea to buy men's shoes if I have wide feet?

Often yes. Converting into men's sizing gives you a wider shoe at the same length, which suits a wider foot. If you have a narrow foot the same conversion causes heel slip.

Do all brands use the same 1.5 offset?

No. Some use one, some use two, and some publish no conversion at all. If a brand publishes its own cross range figure, follow that rather than the general rule.

How does this work for kids and youth sizes?

It does not apply. Children's sizing is not split by gender, so there is no offset. The complication there is the numbering restart, where sizes climb to 13 and begin again at 1 for youth.

What removes the need to convert at all?

A single unisex size run. Atoms uses one range from US 3.5 to 15 in quarter increments, so the same measured foot orders the same size regardless of which range you would normally shop.