Korean Foot Size to US: Use Millimeters, Then Check the Brand

Korean shoe sizes are commonly expressed as millimeter values: 240 corresponds nominally to 240 mm, or 24 cm. As a quick adult-size reference, 240 maps to US women’s 7 or US men’s 6; 250 maps to women’s 8 or men’s 7; and 270 maps to women’s 10 or men’s 9. These overlapping conversions agree in a Korean shopping-service chart and the Adidas US footwear chart, checked September 22, 2026.

Korean-to-US shoe size chart

The values above follow the ranges published in the Korean chart: women’s 220–270 and men’s 240–300. A dash means that source does not provide a conversion for that category, not that the size cannot exist.

Treat this as a quick reference, not a product guarantee. US women’s and men’s scales differ, so “Korean 250 to US” is incomplete unless the US category is specified.

Why the brand and measurement fields matter

Do not turn the chart into a universal mathematical formula. A nominal metric label, a measured foot length and a US size are related, but a manufacturer may not treat them as identical fields.

Nike, for example, explicitly says the CM size printed on its boxes and labels differs from foot length in centimeters. Its chart provides separate size-label and foot-length rows, and its measuring instructions say to use the longer foot and size up when a measurement falls between sizes. The Nike women’s footwear chart carries the same warning.

That distinction matters in a conversion dataset. Put an actual heel-to-toe measurement in foot_length_mm. Put a box or manufacturer size in a separate field such as brand_metric_label. Combining both under a column called cm makes the data ambiguous and can return the wrong lookup.

Width and fit should also remain separate from length. If a source supplies width or model-specific guidance, preserve it in dedicated fields instead of encoding it into the US size.

Structure a publishable lookup table

For a single general reference, a wide sheet is easy to scan:

korean_mm | us_womens | us_mens | basis               | source_url | checked_date
240       | 7         | 6       | nominal metric label | …          | 2026-09-22
250       | 8         | 7       | nominal metric label | …          | 2026-09-22

For multiple manufacturers, use one row per brand, category and metric label:

brand | category | metric_label_mm | measured_foot_mm | us_size | source_url | checked_date

This long format prevents one brand’s value from overwriting another’s and lets readers filter by brand and category. Leave unavailable measurements empty rather than deriving them from the label. Store us_size as text if the data may include values such as 6Y.

Keep source and review dates beside the conversions so readers can identify which chart and version a row represents. If you distribute the underlying file, choose CSV or XLSX according to whether you need a plain interchange table or workbook features.

A clean, non-sensitive reference file can be uploaded to TablePage. As of September 22, 2026, it accepts CSV, TSV, XLSX and XLS files and creates a public dataset page with a filterable table and shareable link.

A lookup table is more useful than a line chart for this data: readers need an exact row, while a plotted line could imply that every intermediate millimeter value has a corresponding US size. Preserve the source-specific distinctions, then direct buyers to the actual brand and model chart before they choose a size.