Finland: a markka from before 1963 is not the markka you think
Finland changed its currency twice in the span this page covers, and only one of the two is the euro. On 1 January 1963 the new markka replaced the old at 100 to 1, cutting two zeros after wartime inflation had averaged around 17% a year. Then on 1 January 2002 the euro replaced the markka at the fixed rate of 5.94573 markka to the euro.
The index chains straight through both events, because an index measures the price level rather than the unit it is quoted in. Your memory does not. An amount you recall from the 1950s is in old markka, and converting it needs both steps.
Suppose a relative remembers paying 2,000 markka for something in 1955. That is old markka. Divide by 100 for the 1963 reform to get 20 new markka, then by
5.94573 for the euro changeover: about EUR 3.36.
Enter 3.36 as the 1955 amount, not 2,000. Skipping the reform overstates the answer a hundredfold, which is the single most common mistake on Finnish figures.
The series starts in 1952, but Finnish price history does not
This page's series begins in 1952, where the Bank for International Settlements anchors its Finnish chain on the cost-of-living index of October 1951. That is a choice about splicing, not a limit of what is known. Statistics Finland's own value-of-money converter runs from 1860, omitting only 1914 for incomplete data.
So if you need a figure from the 1930s, it exists; it simply is not in the chained series used here. Go to Statistics Finland directly rather than assuming the number is unknowable.
The national index includes housing costs the EU measure leaves out
Finland publishes both a national consumer price index and the EU-harmonised HICP, and they are not interchangeable. The HICP excludes owner-occupied housing, mortgage interest, games of chance and tax-like payments, covering slightly under 85% of the national index.
The national index is the one used here, and it is also the operative one in Finnish law: the chained cost-of-living series is what indexes rental agreements for dwellings, business premises and land. If your figure comes from a lease or a pension calculation, the national index is the right comparison.