Method and sources

Card FX tracks what high-demand Japanese-print Pokémon cards cost in Japan, every day, and shows the same price in US dollars. The point is to separate two things that get mixed up: the card's own price move in yen, and the effect of the yen against the dollar.

Where the numbers come from

• Japanese shops: the official Rakuten Ichiba Item Search API and the Yahoo! Shopping item search API. Only in-stock fixed-price items are used. Nothing is scraped.
• Exchange rate: the European Central Bank reference rate for USD/JPY, via Frankfurter, taken at collection time.
• US marketplaces: linked, not quoted. eBay's API licence does not allow eBay data to be combined with other sources or turned into price statistics without eBay's written permission, so Card FX does not use it. A Japan-vs-US comparison appears on card pages only when a US price feed licensed for this use is connected.

How a price is calculated

1. Search each marketplace with the card's name and printed number (for example 217/187).
2. Keep a listing only if its title contains that number. For the Japanese print, drop titles marked as English (英語版, 海外版). For the English print sold in Japan, require such a marker.
3. Drop graded cards (PSA, BGS, CGC and others), lots, sealed product, original packs (オリパ), proxies and supplies.
4. Take the median after removing the cheapest and dearest 10%. At least three listings are needed, otherwise the day is left blank.

These are asking prices, not completed sales. Asking prices react faster but sit above what cards actually sell for, and condition varies between listings.

Index, yen effect and heat

• Card FX Japan Index: equal-weight, chain-linked average of daily changes across tracked cards (Japanese print, Japanese shops). First day = 100. The dollar version converts each day's prices at that day's rate.
• Yen effect: (1 + dollar change) ÷ (1 + yen change) − 1. If a card is flat in yen while the yen weakens 3%, its dollar price falls about 3%, all of it yen effect.
• Heat gauge: Overheated when the price is at least 15% above its 90-day average and up 25% or more over 90 days; Rising when up 10% or more over 90 days; Correcting when 20% or more below its one-year high; otherwise Stable. It needs 30 days of data.

Import math

Card pages convert the Japan price at a rate you can change and add US import duty. The default duty is 12.5%, an assumption you can change: US tariff rules for Japanese goods have changed several times, so check the rate that applies to your shipment. Shipping, proxy-service and payment fees are left out on purpose: they vary by order size.

Matching Japanese and English prints

Each card's English equivalent is checked by hand, artwork included. Some matches are not obvious: the Japanese Mew ex SAR 205/165 has the same art as the English promo SVP 053, not English 151 #193. Each card page says how its prints line up.

Schedule and corrections

Data is collected once a day, early morning Japan time. Days with too few listings are left blank rather than filled in. When a mistake is found it is fixed in the next run.