The quest to create 100% accurate Curta Type 1 Calculators

From Original Drawings

The incredible community of Curta collectors and enthusiasts have painstakingly saved and made public the original engineer drawings.

Curta Type 1R Image
To New Curta

Working from the original drawings, our goal is to reproduce New Curta calculators as accurately as possible using the same aluminum, bronze, and steel materials. 

These will be the first true 1:1 Curta recreations made since 1972.

About the Curta Calculator

Developed by Curt Herzstark while imprisoned during WWII, the Curta Calculator is a mechanical marvel. Its features are quaint by today’s standard but the handheld cylindrical device can rapidly add, subtract, multiple, divide and much more, all with only mechanical gears.

An estimated 150,000 examples of both the Curta Type I and subsequent Type II calculators were produced from 1948 to 1972. During that time, many believed the Curta to be the best mechanical calculator on the market.

Interest in Curta calculators has skyrocketed in the past several years. They are widely sought after as beautiful, yet functional, mechanical objects. Good condition calculators routinely fetch between $1k and $3k USD.

We want to bring the Curta Type I back to life and make Curt’s incredible invention accessible to everyone. Nobody has ever tried to make a new Curta; the calculators are incredibly complex with hundreds of parts. We are up for the challenge! But we need your support.

Curta Timeline

Curt Herzstark started developing plans for a small cylindrical calculator
Curt sent to Buchenwald
First Curta Type I Calculator produced
Last year of Curta production
Curta Project begins

A True Mechanical Marvel

Fully Mechanical

An ingenious mechanism calculates without a single electronic element.

Top Ring

Use the top ring to set the digit and count the rotations

Setting Sliders

Use the sliders to set the operands


Use the crank to run the calculation


Reset the calculator using the finger ring

See how a Curta works

Frequently Asked Questions

How is this even possible?

Thanks to the fervent community of Curta calculator fans, many of the original materials including service manuals and engineer drawings have been preserved. Every component has been scrutinized and documented. That’s the good news. The bad news is that the calculators are incredibly complex with hundreds of parts. Re-creating them and assembling the calculators will not be trivial.

A mechanical calculator? Is this real?

The Curta calculator is a beautiful design object with a rich history. The engineering involved is no less inspiring today almost 80 years after it was invented. At the moment, this site is to gauge interest. Does anybody else beside me want a more accessible Curta Type I calculator? Making a new Curta calculator will be a monumental effort but if enough people want to see this exist, I will make it happen.

Who are you?

My name is Adam Leeb. I’m a product designer and mechanical engineer that loves retro tech. I’ve been fascinated with Curta calculators for a while now but have been frustrated with the ever rising price of genuine Curtas. More people deserve to be able to experience the beauty of a purely mechanical, finely engineered tool in their hand.

How much will it cost?

We are still very early in the project so it is hard to say.  The goal is to create new calculators that look and feel as close as possible to the original at a price that is significantly less than what an original is selling for second-hand. To reach that price point we may have to optimize the internals for modern manufacturing methods however we won’t compromise on materials or finish. Rest assured, the final product will be collector quality.

How can I help?

Please be sure to sign up for updates with your email. Know other folks that would like to see a new Curta exist? Please share this page with them. If I can get to 1000 sign ups then I’ll know there is real interest in the project.