Mechanical Calculators

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Curta Type I

Curta in the hand

Curta Type I.

52 mm diameter x 105 mm high (2" x 4").

Made in Liechtenstein 1948 - 1972.

A stepped gear type calculator capable of the four functions, and more using special techniques.

Curta & container

A Curta and its metal container.

Curta legend

The legend on the bottom.


Curta with 12345789 set and the crank turned once, as shown by the "1" appearing in the white, counter, sector.
This has added the "12345789"  to the accumulator - the black sector.
Turning the crank another revolution would add "12345789" again to the accumulator and the counter would advance to 2.

The ring is used for clearing the accumulator and counter.

Curta with the number 12345789 set.

Curta advertisement

British advertisement for the Curta from 1957.  The prices are in the old Sterling (sd) currency.

This remarkable mechanical calculator is much sought after.  It is a versatile yet very small precision machine with a fascinating history.
It was devised by Curt Herzstark while he was in Buchenwald concentration camp.  He was given a drawing board and was encouraged so that it could be given to the Fhrer.  However, development was completed after liberation by the Americans.
A slightly larger Type II was also produced with increased capacity.

For more information on Curt Herzstark and the story of the Curta see Bruce Flamm's article "The Amazing Curta" in the "Collecting Calculators" section of this site.

To learn more about the life of Curt Herzstark, who designed the Curta, and the amazing story of the Curta's development the Charles Babbage Institute has an oral history transcript with an interview of Mr. Herzstark at

Highly recommended is the YouTube video"How the CURTA Works" at

For much more information about Curta calculators visit "The Curta Calculator Page" and "Curta.Org: Your Complete Curta Calculator Site".

If you do not own a Curta calculator then you can experience one by using the Curta Simulator 'YACS - Yet Another Curta Simulator' authored by Olaf Veenstra.  It takes a little time to start up but it is worthwhile since this incredible simulation also allows you to view the internal workings of the Curta.

Vintage Calculators

Text & photographs copyright, except where stated otherwise, © Nigel Tout 2000-2024.