Bulgaria joined the euro area on 1 January 2026, becoming the 21st member state. All euro-area data on InflationTheGuide now reflects the EA21 composition for figures from January 2026 onwards.
How composition changes affect the index
When a country enters the euro area, it is incorporated into Eurostat's HICP aggregate with a weight proportional to its share of euro-area household expenditure. Bulgaria's weight is approximately 0.7% — comparable to Luxembourg or Malta — meaning its addition has a negligible effect (less than 0.1 percentage points) on the aggregate rate.
Eurostat uses a chain-linking methodology to handle composition changes. Rather than rebasing the entire historical series, Eurostat links the pre-enlargement and post-enlargement indexes at the joining date, preserving historical comparability. This is the same approach used when Estonia (2011), Latvia (2014), Lithuania (2015) and Croatia (2023) joined.
What this means for our data
The basket and weighting structure in our euro-area calculations follows Eurostat's published HICP series directly via the World Bank WDI API. We do not apply any additional adjustments. When Eurostat updates weights or composition, our series updates on the next scheduled data pull — typically within 1–2 weeks of a Eurostat release.
For country-specific comparisons you can view Bulgaria's own 12-month rate separately in the live explorer. Bulgaria's August 2026 rate was 3.8%, slightly above the EA21 aggregate of 3.2% covered in our August release note.
Historical series comparability
Eurostat maintains a consistent EA HICP series that reflects the current composition back to 1997. This means when you look at, say, the 2008 global financial crisis period in our explorer, the data you see uses today's EA21 methodology as far as possible, chain-linked to preserve rates at the time of composition changes. This is standard practice for international statistical agencies.