UK to US shoe size conversion chart for men, women and kids

UK and US shoe sizes look like the same scale because they use the same numbers. They are not. A UK 8 and a US 8 are different shoes, and the gap is not even the same for men and women.

This guide gives you the conversion tables for men, women and kids, explains why the offset differs between them, and covers the one case where the usual rule stops working entirely.

Quick Summary

For men, US sizes run one size above UK, so a UK 8 is a US 9. For women, US sizes run two sizes above UK, so a UK 5 is a US 7. For kids, the offset is roughly one size, but the children's scale restarts at 13, which is where most conversion mistakes happen.

• Men: add 1 to the UK size to get the US size.
• Women: add 2 to the UK size to get the US size.
• Kids: add roughly 1, but watch the restart after 13.
• The offsets differ because the scales were set separately, not because feet differ.
• Both systems step by a third of an inch, so a half size is about 4mm of length.

Here is the quick version.

UK to US: men

Read the UK column, take the US number beside it. The millimetre column is there as a sanity check.

If a brand's own chart disagrees with this one, follow the brand. Their chart reflects the last they build on, which this table cannot know about.

UK to US: women

The women's offset is two rather than one, which catches people out constantly when they buy a men's style in a women's size or the reverse.

UK to US: kids

Children's sizing is where conversions go wrong most often, for one structural reason: the scale restarts.

The restart is the trap. After UK 13 the numbering goes back to 1 and starts again, in both systems, at different points. A US 1 is a bigger shoe than a US 13, which is counterintuitive enough that it causes real ordering errors.

Age guides are a rough sanity check rather than a sizing method, because children of the same age vary enormously. The age based ranges are covered in the kids shoe size chart by age.

Do half sizes convert cleanly?

They convert arithmetically, but not always practically, and the difference matters when you are at the edge of a size.

A UK 8.5 is a US 9.5 for men by the usual rule, and the arithmetic holds all the way up and down the scale. The problem is that half sizes are not offered consistently. Plenty of brands skip half sizes at the top and bottom of their range, so a conversion can produce a size that simply does not exist in the shoe you want.

There are three ways that plays out when you order.

• The half size exists in one country and not the other. A style sold in UK half sizes may be offered only in US whole sizes, or the reverse, because the stock was planned per market.
• The half size exists but sells out first. Middle sizes go first, so the conversion tells you what to buy and availability decides what you actually get.
• The brand rounds for you. Some size guides quietly map two UK sizes to one US size, which hides a 4mm difference inside a single number.

If the exact size is not available, go up rather than down. Extra length can be managed with lacing, a thicker sock or an insole. A shoe that is too short cannot be rescued, and it damages toenails over time.

What should you check when buying across countries?

Cross border shoe buying has a higher error rate than almost any other online purchase, because you are stacking two uncertainties: whether the conversion is right, and whether the brand follows it.

1. Find the brand's own chart first. If it publishes one, it overrides every general conversion including this guide. Brands know their own last.
2. Look for a millimetre or centimetre column. It is the only column that means the same thing in both countries, and it is the one to trust when the others disagree.
3. Read the size selector, not just the guide. What is actually in the dropdown tells you which sizes exist. Guides go stale faster than stock does.
4. Check the returns route before you order. A return that crosses a border can cost more than the shoes, and the higher error rate makes this more likely than usual.
5. Note which market the listing is written for. A retailer selling into both markets sometimes lists one scale and ships stock boxed in the other, which is worth a message to customer service before ordering.

None of this is difficult, but skipping it is why so many people end up with a shoe that is technically the right converted size and still the wrong fit.

Why is the offset different for men and women?

Not for any reason to do with feet. The two scales were set independently and then never reconciled.

Both the UK and US systems descend from the same measuring tradition, but the US adopted its scale with a different starting point from the UK, and the women's scale was set separately again. The result is an offset of one size for men and two for women, which has persisted because changing it now would invalidate every shoe box in circulation.

This also explains why the men's to women's offset within US sizing is about one and a half rather than a round number. It is the residue of two scales that were never designed to line up.

How big is one shoe size?

A third of an inch, or about 8.5mm, in both the UK and US systems. That unit comes from the barleycorn, an old English length measure, and it is why shoe sizes step in such an awkward amount.

A half size is therefore about 4mm. That is the entire margin you are working with when you decide to size up or down, and it is why fit advice that says just go up a size is usually bad advice: you are adding 8.5mm of length to solve a problem that might need 3mm.

It is also the argument for finer increments. A quarter size is about 2mm, which is close to the precision your foot actually distinguishes. Atoms is offered in quarter increments from US 3.5 to 15 for exactly that reason.

When does the conversion fail?

Four situations, in rough order of how often they bite.

• The brand uses its own scale. Plenty do, especially for sports and outdoor footwear. Their chart beats this one every time.
• You are crossing the kids and adults boundary. The restart at 13 plus the youth numbering makes this the highest error zone of all.
• The shoe shape is unusual. A sharply pointed or very rounded toe changes the length you need, and no offset accounts for that.
• You are at the ends of the range. Conversions are tuned to the middle of the scale and get looser at the smallest and largest sizes.

If you have wide feet, the conversion is not the main problem. Length and width interact, and the usual fix for a wide foot is a quarter size of extra length rather than a different conversion. That is covered in best minimalist sneakers for wide feet.

How do you avoid converting at all?

Measure your feet in millimetres and work from that number instead.

1. Stand on paper with your heel against a wall. Standing, not seated, because feet lengthen under load.
2. Mark your longest toe, which is not always the big toe.
3. Measure in millimetres from the paper edge to the mark.
4. Do both feet and keep the larger figure.
5. Measure late in the day, when your feet are largest.

With that one number you can read any chart in this guide from the millimetre column rather than converting between two national scales that were never designed to agree. The same logic applies to millimetre based systems, which is covered in Korean shoe size conversion.

Does the right size change through the year?

Slightly, and enough to matter if you are converting at the edge of a size.

Feet swell in heat and after long periods standing, and they are measurably larger at the end of the day than at the start. Add a thicker winter sock and the effective fit can shift by close to a quarter size between January and July. That is why a shoe bought in one season can feel wrong in another without anything having changed about the shoe.

Two practical conclusions follow. First, fit for the thicker sock you will actually wear, and accept a slightly roomier fit in summer, rather than the other way round. Second, if a converted size lands exactly between two available options, the season you are buying in is a reasonable tie breaker.

What to do with this

If you are buying once, use the tables: add one for men, two for women, and double check anything involving children's sizes. If you buy across systems regularly, spend two minutes measuring instead, because the measurement does not expire and the conversion rules keep producing the same small errors.

The deeper point is that a conversion chart is a workaround for scales that disagree. The more precisely a brand sizes its shoes, the less the conversion matters, because you are matching a measurement rather than translating a number.

Frequently asked questions

How do I convert UK to US shoe sizes?

For men, add one, so a UK 8 is a US 9. For women, add two, so a UK 5 is a US 7. For kids the offset is roughly one, but the scale restarts after 13.

Why is the offset different for men and women?

The two US scales were anchored at different starting points from the UK scale and never reconciled. It is a quirk of how the scales were set rather than anything to do with feet.

Is a UK 8 the same as a US 8?

No. A UK 8 is about a US 9 in men's sizing and about a US 10 in women's. The two systems share numbers but not starting points.

How much length is one shoe size?

About a third of an inch, or roughly 8.5mm, in both the UK and US systems. A half size is therefore about 4mm, which is the whole margin you work with when sizing up or down.

How do UK to US kids sizes work?

Add roughly one, but watch the restart. Children's numbering climbs to 13 and then begins again at 1 for youth sizes, so a US 1 is a larger shoe than a US 13.

Do half sizes convert cleanly between UK and US?

Arithmetically yes, but they are not offered consistently, so a conversion can produce a size that does not exist in that style. If your size is unavailable, go up rather than down.

Which column should I trust when charts disagree?

The millimetre or centimetre column, because it means the same thing everywhere. After that, trust the brand's own chart over any general conversion.

Does the right size change through the year?

Slightly. Feet swell in heat and at the end of the day, and a thicker winter sock can shift the effective fit by close to a quarter size. Fit for the thicker sock you actually wear.