The Curta

The Curta Mechanical Calculator has an interesting story, a hoon tie-in, and is just nerdtastic. Conceived of in Vienna by Curt Herzstark in the 1930s, the single-drum Curta was quite the advancement over contemporary calculators, many of which used 10 or more drums. Using 9s compliment math, the Curta could add and subtract all in a single drum. It would be a design that would be used up through the 1980s.

In 1938, while still working on the calculator, Herr Herzstark was forced to stop work and concentrate on measuring instruments and distance gages for the German Army. Herzstark, whose father was Jewish, would find himself in the Buchenwald concentration camp in 1943. With nothing but time on his hands, he picked up his development of the Curta calculator. He was given access to paper, pencil and a workshop by the camp’s work scheduling department. The plan was, if it worked, to give one to Hitler upon winning the war, and Herzstark would be made an honorary Aryan.

Germany didn’t win the war, and Herzstark was freed by the Americans and soon found a factory that could build his invention. He fled the Russians and went to Austria where he sought financial backing. The Prince of Liechtenstein saw promise in the Curta and helped form a new company, Contina AG Maura. Contina would produce the Curta up to the early 1970s.

A slightly disassembled Curta showing the slides and the stepped drum behind them.

To add, you input a number using the slides on the sides and rotate the crank. The inputed number is added to the number of revolutions shown in the revolution counter and the result is displayed in the results counter. Subtraction is similar, but the crank is raised along its axis and the result is the number of revolutions to return the results counter to zero. Multiplication and division use a series of crank and carriage shift operations.

The Curta was considered the best hand-held calculator until the advent of inexpensive, small electronic calculators in the 1970s. It was used by Time-Speed-Distance rally racers into the 1980s, when electronic timing calculators could finally take the abuse of rally driving. It was also used by pilots to calculate weight and fuel load. Its design made it both rugged and nearly fool proof since each step was displayed in one of the counters.

Today the Curta is still sought by collectors. It’s a relic from a bygone era where mechanical engineers bested electrical engineers.

Hat tip to Tim Odell for the suggestion!

(Lead image by Rama; used by permission from Wikimedia)

  • Charles_Barrett

    Some mechanical devices were truly amazing in their precision and accuracy. The U.S. WWII Norden bombsight is another one that comes to mind:
    <img src="; width=500>

    • The Norden bombsight is a mechanical wonder.

  • I have never seen or heard of such a thing before. Previously I thought the only non-electronic calculating devices were scribers, abacuses and slide rules. What a marvelous little machine! I'd love to find one to take apart and appreciate, but I have a sense I should know better than to search for one – my wallet will thank me for such abstinence.

    • When I was reading up on the Curta I read that something like 2/3 of all Curtas were returned to the factory. Only a few had actually broken, but most were taken apart and the owners couldn't get them back together. The mechanism uses a series of precision cut rings and pins that only fit in a certain order. Like a puzzle. The joke was that a Curta actually cost $900 — $600 to buy it and $300 to have it repaired after you took it apart.

      • So you're saying there'd be pieces left over? Feh! That's what you need to have for Imperial-Metric conversion!

  • At first, I thought this was a camera lens that you could crank out to telephoto. Damn, that would be awesome.

  • P161911

    I can't believe the prices these things are going for, $800 and up!!

    • I know. If it's in excellent condition it will be over $1000. I so want one, though.

  • I think I win the award for the largest lead-in image.

  • red

    Enjoy some more pictures of the Curta, also a lot of curta advertisement and manuals… (<-open-<)

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