the NL cup index
the median cost of a cup of Dutch specialty coffee, at a 15g dose — one number, refreshed monthly.
monthly reading
not enough monthly history yet for a trend line — check back next month.
methodology v1.0
we track roasted whole-bean and ground coffee listed for sale by Dutch specialty roasters. multi-bean tasting packs and gift boxes are excluded — a per-cup number is meaningless for a box of six small samples — along with non-coffee products (drinks, gear, capsules, merch).
each bean's price is converted to zł/cup at a fixed 15g reference dose (a neutral filter-coffee serving), from the bag size actually listed. this reference dose is pinned to the series and does not follow the site's adjustable zł/cup dose slider. the median (not the average) is used so one very expensive or very cheap outlier can't move the number.
the monthly series is backfilled from our observation archive: each month's reading is the carried-forward price in effect at that month's end, for every bean tracked by then — so early months, with fewer roasters on the radar, carry a smaller sample (shown per month above).
this is a defensible default, not a settled standard: whether a trimmed mean would serve better than a median, the exact inclusion rule, and which day of the month the reading is taken on are all open questions. the methodology version above changes whenever the underlying rule does, so a cited number can always be traced back to the exact rule that produced it.