The white LACK side table, article 30449908 , costs €9.99 in Germany, France, Spain, Austria and Belgium. In Portugal the same article number costs €12.99. Same product, same currency, a 30% gap, and no exchange rate to blame.

I wanted to know whether that was a quirk of one cheap table or a pattern, so I built a small IKEA price index in Python: the same article numbers, priced in nine euro-zone countries on the same day. It is a pattern. Not one of the 72 articles I could match had the same price in all nine countries, and on average the French site charges 37% more than the Dutch one for identical items.

The data

I used the IKEA Pro API , which returns IKEA's catalogue as JSON for a given countryCode .…