A couple of type 1s up for auction right now include dated documentation:

#57756 dated April 1966
#77545 dated 9/11/67

Tens of months indeed.

From the pictures, these are dates of sale/receipt as usual, not factory production dates.

Just to resurrect this old, but always fascinating thread -
there has been an official factory serial number list posted on the "curta.li" site. It should allow to calculate the production date of your curta with much more precision.

You will find it under "Anleitungen"

... yes, it's here:


Curta type 1 & 2 - calculate the date of production


thanks stenella !