Curta Dating

Last Update: February 19, 2007 -- THE CURTA REFERENCE

CURTA I : YEAR = 1947 + ( SERIALNR / 80,000 ) x 24

Example: Serial Number = 15045

1947 + (15,045/80,000) x 24
1947 + .18806 x 24
1947 + 4.5135
1951.5135
12 x .5135 (now take the fractional part and convert to months)
6.1620 = early July
~ July 1951

Example: Serial Number = 58562

1947 + (59,862/80,000) x 24
1947 + .74828 x 24
1947 + 17.9586
1964.9586
12 x .9586 (now take the fractional part and convert to months)
11.5032 = Mid December
~ December 1964

CURTA II: YEAR = 1954 + ( (SERIALNR - 500,000) / 70,000 ) x 17

Example: Serial Number = 526699

1954 + ((526,699-500,000) / 70,000) x 17
1954 + (26,699 / 70,000) x 17
1954 + .3814 x 17
1954 + 6.4840
1960.4840
12 x .4840 (now take the fractional part and convert to months)
5.81 = late June
~ June 1960

Facts from Rick:

• CUTRA 2s started at serial number 500,000.
• CUTRA Is were first produced from 1947 to 1970.
• CURTA IIs were first produced from 1954 to 1970.
• Curt Herzstark heard 150,000 to 160,000, maybe even more CURTAs were manufactured.
• Oldest Type I: 2019
• Newest Type I: 80288
• Total Type I: 78,269
• Oldest Type II: 500084
• Newest Type II: 569944
• Total Type II: 69,860
• There are +/- 80000 Curta I and +/- 70000 Curta II machines.
• The first production began on April 1947.
• In 1949, only 300-400 CURTAs were made each month.
• By 1952, 1,000 CURTAs were made each month (My calculations show only 555 were made each month)
• The CURTA II was first produced in 1954
• The last CURTA was made in November 1970
• CURTAs were sold until early 1973.

Notes and Original Formula From Erik van Dam:

I found somewhere that there are +/- 80000 Curta I and 60000 Curta II machines.

They were made from 1948 until +/- 1972 so if they have made the same number of machines every year, and I am sure they did not, you could use the next formulas to calculate the estimated year of production:

Curta I : YEAR = 1948 + ( SERIALNR / 80,000 ) * 24
Curta II: YEAR = 1948 + ( SERIALNR / 60,000 ) * 24

If the production numbers are correct you should be at least somewere in the right direction.

It is possible that there is a offset that has to substracted from the serial number first. So if anyone can tell the lowest and highest serial number for the Curta's I and II then I can perfect the formula!

Erik van Dam
0vdam03@flnet.nl

From Reinmar Wochinz:

The production of the Curta I started with #1, the Curta II started with #500.000. The number of Curtas produced is approximately what Erik van Dam stated.

I myself have three Curtas at the moment:
#32.133 Curta I (open demonstration model)
#55.176 Curta I
#512.754 Curta II

Curtas I had in the last few years were
Curta I: #38.100, #54.788
Curta II: #515.417, #531.566

Reinmar Wochinz
Vienna - Austria
rwochinz@pop.tuwien.ac.at

Notes from Rutger Verbeek:

I have a very late (unused) Curta II, serial number 560608. I think that the last 5 digit are the production number.

Rutger Verbeek
Rutger.Verbeek@FernUni-Hagen.de