Bulgaria to join euro area on 1 January 2026

This will likely come with a one-time significant increase in inflation, at least based on other European countries.

When Germany converted to the Euro, the conversion rate was (IIRC) about ~2 DM to the Euro but from what I recall, a lot of everyday things went from costing 7 DM to 7 euro, effectively doubling in price. IIRC France was similar (ie ~6.5 francs to the Euro but 10 Francs went to 3 euro, etc).

I've tried searching for any studies on this to see if the effect was measured and, if so, whether it held with later countries joining the euro.

I'm a little surprised that the euro has been this stable for this long (going on 30 years). Finland debated leaving. IT's debated if there's even a legal mechanism to leave. We still have the problem that the ECB sets eurozone monetary policy with Germany and Greece being vastly different economies.

I was in Belgium the week the Belgian franc converted to Euros. I saw no price changes other than rounding up or down to the nearest Euro equivalent price. If memory serves some stores showed prices in both denominations for a while which would not have allowed for stealth inflation to happen.

The currencies were pegged for a period before then so other than niche cases there really weren’t opportunities for massive price increases.