Mastering the Conversion: The Definitive Guide to Chinese (CN) to US Shoe Sizing

For those of you scanning this while checking out, here is the executive summary on how to Convert Chinese Shoe Sizes to US.

• The Logic: CN sizing generally equals the length of the foot in millimeters divided by 10, or simply the centimeter length. For example, CN 240 is for a foot that is 240mm (24cm) long.

• The Rule of Thumb:

  • CN 35 ≈ US Women's 5
  • CN 36 ≈ US Women's 6
  • CN 37 ≈ US Women's 6.5
  • CN 38 ≈ US Women's 7.5
  • CN 39 ≈ US Women's 8.5
  • CN 40 ≈ US Women's 9 / Men's 7
  • CN 41 ≈ US Women's 9.5 / Men's 8
  • CN 42 ≈ US Women's 10.5 / Men's 8.5
  • CN 43 ≈ US Women's 11 / Men's 9.5

• The Caveat: Chinese lasts (the mold shoes are built on) tend to be wider at the forefoot but shorter in the arch length compared to US lasts. If you are between sizes, always size up.

To master the fit, you must understand the architecture of the measurement. The US system is complicated, relying on half-sizes that represent 1/6 of an inch difference. It is disjointed and varies heavily between brands (a Nike US 8 is rarely a Steve Madden US 8).

Chinese shoe sizing is far more pragmatic. It is a direct reflection of foot length. If you see a size labeled 24.5 or 245, that is the literal length of the foot the shoe is designed to accommodate in centimeters or millimeters.

However, the confusion arises when CN sizes are simplified into two-digit numbers (like 38, 39, 40) that look deceptively similar to European (EU) sizes. Do not conflate CN and EU sizes. A CN 40 is typically smaller than an EU 40. An EU 40 is roughly a US Women's 9.5-10, whereas a Cn40 shoe size is closer to a US Women's 8.5 or 9. Treating them as identical is the most common reason for returns.

When curating a wardrobe, precision is key. Use this breakdown to navigate the specific conversions that cause the most friction for US shoppers.

The Common Range (CN 34 - CN 40)

Most mass-market fashion footwear from Asia caps out at size 40.

• CN 34: US 4.5 (220mm)

• CN 35: US 5 (225mm)

• CN 36: US 6 (230mm) — Note the jump here; US 5.5 is often skipped or grouped.

• CN 37: US 6.5 (235mm)

• CN 38: US 7.5 (240mm)

• CN 39: US 8.5 (245mm)

• CN 40: US 9 (250mm)

The Hard-to-Find Range (CN 41 - CN 43)

If you wear a US 9.5 or above, sourcing footwear from Asian retailers requires vigilance. This is where the queries regarding Cn42 shoe size to US women's become critical, as many size charts are inaccurate in this upper range.

• CN 41: US 9.5 (255mm). If you have a wide foot, this will feel tight; consider the 42.

• CN 42: US 10 to 10.5 (260mm). This is the gold standard conversion for Cn42 shoe size to US women's. If you are a true US 10, this provides a comfortable fit. If you are a 10.5, it is a performance fit (snug).

• CN 43: US 11 (265mm). Addressing the Cn43 shoe size to us women's query: this is rare in fashion footwear but common in unisex sneakers. It fits a foot length of 26.5cm.

Before checking out, I highly recommend cross-referencing with our internal Shoe Size Converter (Intl) to ensure you aren't dealing with a brand-specific anomaly.

Men's footwear requires a different calculation because the width-to-length ratio differs in the male last.

• Cn40 shoe size: Corresponds to a US Men's 7.

• Cn41 shoe size to US: This is a solid US Men's 8.

• Cn42: US Men's 8.5 to 9.

• Cn43: US Men's 9.5.

• CN 44: US Men's 10.

• CN 45: US Men's 11.

• CN 46: US Men's 12.

Stylist Note: If you are buying boots or high-top sneakers, always add 0.5 to your US size requirement before converting to CN. The instep height on Chinese lasts is often lower than American men are accustomed to.

Sizing is 3D, but charts are 2D. This is where most people fail. You can get the length right—successfully matching Cn41 shoe size to US—but still find the shoe unwearable. Why? Volume.

Chinese footwear is typically built on a last that assumes a slightly wider forefoot but a significantly narrower heel and lower instep (arch height) compared to the standard US 'B' width.

The "Wide Foot" Myth

There is a misconception that Asian sizing is universally narrow. In reality, the toebox is often quite accommodating. The tightness usually occurs at the vamp (where the toes meet the foot) and the instep.

• Low Volume Feet: If you have flat feet or low arches, CN sizing will likely fit you better than US sizing because there is less gap between the top of your foot and the shoe material.

• High Volume Feet: If you have high arches, you must size up. Even if the length of a CN 40 is correct for your foot, the lack of vertical space will cut off circulation.

If you are shopping for pumps or stilettos, the pitch matters immensely. Consult our Heel Height Guide to understand how the angle of the foot affects the volume requirement within the toe box.

As a capsule wardrobe architect, I calculate Cost-Per-Wear (CPW). A shoe that doesn't fit has an infinite CPW because you never wear it. The material dictates how risky your size conversion is.

1. Genuine Leather

If you are eyeing a pair of leather boots in CN 42, and you are a US 10.5, you are safe. Leather is organic; it has memory. It will relax and mold to your metatarsals within 3-4 wears. You can afford a snug initial fit.

2. Synthetics (PU/Vegan Leather)

This is where Convert Chinese Shoe Sizes to US gets tricky. Polyurethane (PU) has zero give. It is essentially plastic. If the chart says CN 40 is 250mm and your foot is 250mm, do not buy the CN 40 in PU. You need millimeters of clearance for your toes to splay when you walk. Size up to CN 41.

3. Performance Knits (Sneakers)

If you are looking at the latest release on our Sneaker Drop List, know that knit uppers offer the most forgiveness. You can often size down half a step in knits for a locked-in fit.

Do not rely on the size you wore five years ago. Feet change shape with age, gravity, and lifestyle. Before ordering an international shoe size chart item, get your exact millimeter measurement.

1. The Setup: Place a piece of paper on the floor, flush against a wall.

2. ** The Stance:** Stand on the paper with your heel firmly touching the wall. Wear the type of socks you intend to wear with the shoes (critical for boots!).

3. The Mark: Trace the longest part of your foot (usually the big toe or the second toe). Keep the pen perpendicular to the floor—do not angle it in or out.

4. The Math: Measure the distance from the edge of the paper to your mark in millimeters.

• Example: If you measure 253mm, you are not a CN 40 (250mm). You are a CN 41 (255mm). Never round down.

Different shoe architectures require different allowances.

Boots

Boots are high-stakes because they enclose the ankle and instep. When converting Cn43 shoe size to us women's for boots, verify the calf circumference if it's a tall boot. Asian sizing often assumes a slimmer calf. If you are athletic, look for "elasticated gore" in the product description.

Heels and Pumps

For high heels, the foot slides forward due to gravity. If you size up too much, your heel will slip out. Stick to the exact millimeter conversion. If you are exactly 240mm, get the CN 38. Do not size up to 39 unless it is a pointed toe box.

Sandals

You have more leeway here. A Cn40 shoe size sandal can often accommodate a US 9.5 foot because the open toe and heel allow for overhang. However, ensure the arch strap hits the correct point of your foot to avoid blistering.