Cover picture © Credits to iStock / Stefan Rotter
Cover picture © Credits to iStock / Stefan Rotter
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The Curta, a calculator that connected Liechtenstein and Vienna

3 minutes to read

The Curta is a small compact calculator that was widely used in the second part of the 20th century until its replacement by electronic calculators in the 1970s. It is still perceived as a marvel of mechanical miniaturisation. All calculators were produced in the Curta factory in Liechtenstein, under the design of a Vienna-born engineer Curt Herzstark.

Picture © Credits to Wikipedia / Thomas Schanz
Picture © Credits to Wikipedia / Thomas Schanz

Designed in a concentration camp by Curt Herzstark

The designer of Curta calculator, Curt Herzstark, was born from a Jewish father and a Austrian Christian mother. His father was the owner of a company that produced calculators, where he was working as a technical manager. Numerous contacts with customers showed him that a pocket-sized calculator would be in great demand. So, he decided to design the first pocket-size Curta calculator prior to the World War II. However, its development was interrupted by the war, and the company started producing detonators for German Army instead. Already in 1943, Curt Herzstark was arrested as “a half-Jew” by Nazis and sent to the Buchenwald concentration camp. Due to his technical skills and innovative mind, Nazis treated him as an "intelligence-slave".  There, he was appointed the head of a department that dealt with the production of mechanical precision parts, including the parts for the production of notorious V2 rockets.

Picture © Credits to flickr / stanze
Picture © Credits to flickr / stanze

After the liberation, he returned to Vienna. He worked out the basic design of the calculator in his head and developed it on paper when he was released in 1945.  However, he was not able to find a financial backer to start the production of his invention. Finally, he was invited to Liechtenstein, where a factory was founded to produce the Curta. This pocket-size calculating machine went into production in 1948 and was manufactured until 1971.

The Curta calculator's design

The Curta is a mechanical calculator in the form of an 85-millimeter high cylinder that has a diameter of 53-millimeters. It was made to be comfortably held in one hand, while you enter the numbers with your fingers via a control slide, and then triggered the arithmetic process via a crank. Besides being much smaller, they were also faster and quieter than their older, larger hand-driven ancestors. They were far less noisy, and only a little slower than the motor-driven models.

Two models were produced. The Curta I delivers the eleven-digit results and consists of 571 individual parts, while the second generation delivers the fifteen-digit results and consists of 719 parts.

Operations

The Curta masters four basic arithmetic operations, and the later manuals included the algorithms for cubes and square roots. All calculations are being attributed to additions and subtractions. I don’t want to be too much technical here, so if someone wants to know how it actually works, you can see it in the video below.

It was used primarily by merchants, technicians, architects, engineers, chemists, and scientists. The machine can be comfortably held in one hand and operated largely with one hand.  The Curta was made solely of metal, and its corrosion resistance and robustness, which was confirmed in long-term tests, allowed it to be taken and used anywhere. 

A total of about 140,000 copies of the Curta were produced by 1971. Due to its superiority and handy design, it dominated the market until the early 1970s, when it was quickly replaced by electronic calculators (HP-35). The price of the Curta was high, and today, it is regarded as the collector’s item and reaches very high prices.

The Curta is still considered the world's smallest industrially produced, mechanical, pocket-size calculating machine, and it changed the everyday life a few decades ago. More about this mechanical marvel, you can find out in the Museum Mura in Liechtenstein and the Vienna Technical Museum.


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The author

Ogi Savic

Ogi Savic

I am Ogi. A journalist and economist, I live in Vienna and I am passionate about skiing, traveling, good food and drinks. I write about all these aspects (and more) of beautiful Austria.

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