Women's Chinese shoe sizes often use EU-style CN labels. The US result depends on the women's size scale, not the men's one.
Quick answer: CN 38 is about US women's 7.5. CN 40 is about US women's 9. CN 41 is about US women's 10.
CN 39 is about US women's 8.5 and 24.5 cm foot length.
CN 40 is about US women's 9, but use 25.0 cm as the final fit check.
The same CN size has a different US label for men's shoes.
Chinese shoes can run narrow, so check seller notes for width.
This page answers one specific size search intent. For the best fit, start with the linked main converter and use the centimeter measurements on the Chinese chart whenever they are available.
Marketplace labels are useful shortcuts, but brand charts, garment type, fabric stretch and body measurements can change the final fit. Treat the lookup as a nearest match, not a guaranteed size.
Chinese size labels are practical lookup shortcuts, not universal brand guarantees. A CN shoe label, clothing size, bra code or Taobao chart row can vary by seller, product category, last shape, fabric stretch and whether the chart shows body measurements or garment measurements.
When possible, use the centimeter value first: foot length for shoes, bust/waist/hip for clothing, under-bust and cup difference for bras, and the specific Taobao chart row for marketplace listings. Then use the converter result as the nearest US, UK or EU match.
For the broader explanation, read Chinese shoe size chart to US complete guide. For why these pages give estimates instead of promises, read Chinese shoe sizes and foot length.