Add it All Up With a Curta Calculator

The Curta calculator is a collector's item and one of the first portable calculators. The machines were first designed in the 1930s and have been used in the aviation and racing industries for many years. These unique items found for sale on eBay can give you a glimpse into the history of early calculating devices.

What is a Curta device?

This fascinating machine is a mechanical calculator, developed by Curt Herzstark in the 1930s. It was based on the designs of the stepped reckoner and the arithmometer. They were considered one of the first modern calculators in the world. The numbers are entered using one of the slides and the result and revolution counters are on a shiftable carriage. With a single turn, the input number is added to the total calculation. The machine can subtract numbers by pulling the crank upwards before a turn. Division and multiplication also can be performed by shifting and cranking the carriage. This small cylinder device is extremely compact and is also known as the "pepper mill," the "grinder," and the "math grenade."

How many models were produced?

There were two models of the device produced. They include:

  • Type I: This is also known as a setting slider. It has eight digits for use in data entry. It features a six-digit revolution counter and an 11-digit counter. There were over 80,000 of this model produced.
  • Type II: This is the larger of the two models and was introduced in 1954. It has an eight-digit revolution counter and a 15-digit result counter. They began production in 1966; by 1972, all models were discontinued.
Are there protective cases available for this machine?

The machines were originally sold with a protective case or capsule. You can still find these devices sold in their original cases. On eBay, they are often metal or plastic screw-top cylinders with an internal lining for extra protection. The plastic models were not suitable for mass production and were quickly replaced by metal cases. It is rare to find a plastic case on the secondary market. Some owners even had leather cases specially made for their instruments.

Content provided for informational purposes only. eBay is not affiliated with or endorsed by Curta.