CURTA in Hand

The CURTA Calculator Page

Last Update: December 31, 2003 -- THE CURTA REFERENCE



Introducing the classic Curta Calculator poster for all Curta fans. This fabulous poster shows a detailed layout of the inner working of Curt Herzstark's amazing machine. All Curta parts are close to actual size and displayed in multiple exploded views. Every part is labeled with its original name as designated in the Contina A.G. factory service manual. The elaborate and detailed poster design was nearly a year in planning and execution. Original factory photographs, drawings and artwork have been combined with new imagery to produce this engineer's view of a mechanical masterpiece. Many thanks are due to Carl and Jack for their encouragement and enthusiasm.

The Curta Calculator poster is very suitable for framing and will make a wonderful gift to any Curta enthusiast. It is an essential element in any Curta collection.

The poster measures 24 1/2" (62cm) in width and 16" (41cm) in height and is printed on high quality Strobe Gloss 100 pound paper. The poster will be shipped in a rugged 3"x18" Kraft Mailing tube.


Within the United States and Canada

The cost is $19.95 plus $5.05 for USPS Priority shipping in the US and Airmail postage to Canada.

You can pay now with PayPal

(click here for US and Canada)
You can pay by mail with a money order Poster&BODY=I'm interested in the Curta Poster. Please send me ordering information. My address is:.

For International Purchasers

The cost is $19.95 plus $8.05 for USPS International shipping.

You can pay now with PayPal

(click here for International Shipping)
You can pay by mail with a money order Poster&BODY=I'm interested in the Curta Poster. Please send me ordering information. My address is:.

Pay me securely with any major credit card through PayPal!

Buyer Feedback!

  • The poster arrived yesterday and it's terrific!   You did a really great job on it and I'd think any Curta collector will want one too.   What a great idea you had and thanks again so much for creating it. -- Greg -- Hillsboro, Oregon   USA

  • The poster was received today in perfect condition.   I thank you for your prompt and friendly service.   I'll be framing it and hanging it in my den. -- Jim -- Beachwood, Ohio   USA

  • Thanks!   This will hang in my office at NASA.   I have a Curta that I inherited from my great Uncle. -- Donald -- Huntsville, Alabama   USA

  • I received it a couple of days ago... Thank you!   It's wonderful!   Now I just have to find a frame and it will hang in pride of place in my house. -- Cath -- Bedfordshire, United Kingdom

  • Your wonderful Curta poster arrived well yesterday.   Thanks and best regards from Germany. -- Hermann -- Bayern, Germany

  • I have received the wonderful curta poster and I am inspired.   I congratulate you too this excellent poster. -- Bernd -- Langerwehe-Schlich, Germany

  • I received the Curta poster and it is beautiful to my eyes.   Even the sturdy custom mailing tube is a keeper.   I have the poster displayed temporarily in a poster frame with a thin plastic cover until I have a permanent frame made for it. -- Robert -- Alpine, Texas   USA

  • Hi Rick.   Just a quick note to let you know the Curta poster arrived today.   I am VERY pleased with it and plan to frame it for my office.   Thanks again! -- Sam -- Ridgecrest, California   USA

  • Rick - the Curta poster is absolutely fabulous, both the production quality and the concept.   It's something NO Curta Home should be without. -- Skip Godfrey -- Billings Montana   USA

  • Hi Rick, thanks a lot, I just received the poster!   It is fantastic, really well done.   Greetings from Madrid, Spain -- Angela

  • Speedy, secure shipment of an excellent product.   Great gift!   Thanks.   A+++ -- Bruce -- Okemos, Michigan   USA

  • The Curta poster is great.   I'm very pleased.   Sent quickly, too.   Thanks! -- Paul -- Hartland, Michigan   USA

  • Really beautiful item.   Really fast ship.   Thanks for a perfect transaction!! -- Kerry -- Sayre, Pennsylvania   USA

  • Excellent item, fast ship and well packed A+++++ -- Brian -- Lawrence, Kansas   USA

  • Thanks for the poster that I just bought.   It is great. -- Mark -- Santa Clara, CA   USA

  • Hi Rick, Received the poster today.   BEAUTIFUL!!!!   I left very positive feedback.   Thanks again -- Tom -- Stoughton, Wisconsin   USA

  • Hi Rick -- Beautiful job on the poster!   'twill be framed soon. -- Larry in Springboro, OH   USA

  • The Curta poster is wonderful!  Thanks so much.   --   Pam - Tucson, AZ  USA

  • Hi Rick, The poster arrived today—it’s fantastic!  Absolutely beautiful!  Thanks, Bob - Palo Alto, CA  USA

  • Rick, Your work is outstanding!  The poster is amazing; I've been studying it since it arrived.  The detail and quality of the photos is excellent and the amount of data you have included is impressive.  I noticed your name in the CURTA article in the January [2004] Scientific American (in the box on page 98 where the author, Cliff Stoll, thanks his elves) and now I know the source of some of the photos in the article since I visited your web site. -- Charlie -- Randallstown, MD   USA

Countries Sold To (so far)

  • Australia
  • Canada
  • France
  • Germany
  • Ireland
  • Israel
  • Italy
  • New Zealand
  • Portugal
  • Spain
  • Sweden
  • Switzerland
  • United Kingdom
  • USA

Jan Meyer's Fantastic Curta Simulator!

The Simulator

A complete Curta simulation, with which all arithmetical examples can be accomplished.

You don't have Curta? Then you can use the Curta simulator .
It needs Flash Player 6, which you can download here free of charge.

Visit Jan's Curta Web page:

Ray Traced Curta

Curta Type II Ray Traced Picture!

Here is a great picture created by
John Cherry. He was learning to use ray tracing software (POV-Ray 3.02). This is a picture of his Curta Type II (number 546692).

The picture uses 16 Million colors.

There are equivalent versions of POV-Ray for MS-DOS, Windows 95/98 & x86 NT, Macintosh, PowerPC, Amiga, SunOS, Linux (on Intel platforms) and generic Unix.

Great Job John!


The CURTA Collectors and Registry Page

The CURTA Collectors and Registry Page is a list of people who collect/own/like CURTAs!

Disassembly Disassembly

The Curta Disassembly

Well I finally did it. Thanks to the support of my friend Carl I fully disassembled a type 1 Curta. The really good news is I put it back together and it still works! This page is BIG so go here only if you have a high speed connection or the time to spare. Each picture can be clicked on for a larger view too. -Rick-

Curt Herzstark - The Man

I've received a number of e-mails asking for pictures of Curt Herzstark. Unfortunately the few shots I had are poor 3rd or 4th generation Xerox copies:

Magazine Curt Newspaper Curt Factory Curt Old Curt

Luckily Prof. Karl Kleine from Jena, Germany has just discovered some original pictures of Curt (click on these pictures for a larger version):

Young Curt-1910 Factory Curt-1950 Curt-1985 Curt-1985 Curt-1987

Demo Curta

The CURTA Demo Collection Page

The CURTA company produced demo units for their sales force. According to a conversation with a factory trained repair technician, they only produced one demo unit per country that the Curta was sold in. If you own a Demo unit, send me a picture and I'll register it on the Curta Demo page.

Demo Curta Demo Curta Demo Curta
Demo Curta Demo Curta Demo Curta

The Oldest Known Curta

Here are the before and after pictures of Curta 2185.
It had extensive damage due to water contamination.
The Curta was sent to Jack Christensen for a major overhaul.

It was discovered in a flea market antique shop in Montevideo, Uruguay. The original owner of the Curta was a busineman in Montevideo who used to import merchandise from Europe. He died and his wife sold it to get some extra money.

Jack sent some great emails detailing the restoration process. A compilation of those emails can be found at the following link:
Restoration of the oldest Curta...

Demo Curta Demo Curta
Demo Curta Demo Curta

Curta Manufacturing Evolutions

Here are three different styles of type 1 Curtas. Notice the difference between the handle top, the entry knobs, the labeling/lettering, and the storage cans?

Demo Curta Demo Curta

Curta Prototypes

Details of these early prototypes can be seen in some of Curt's patents.

Some Nice Curta Photos

Demo Curta Demo Curta

CURTA MODEL II calculator, NM w/case Item #541588446

These two pictures were taken by Rick Spaulding. He used an Olympus C-3030 and a Dynalite studio strobe kit for lighting.

Demo Curta

Here's another nice picture I found on the Internet, unfortunately I don't know who took it.

HGA Curta

The Helmut G. Ayen Collection

The Helmut G. Ayen Collection Page is a set of 33 beautiful pictures that I was sent from Helmut Ayen in Hossingen, Germany. He not only owns a pair of type I and type II Curtas but also a pair of type I and type II Demo Curtas! Enjoy the pictures and as always, click on any picture to get a larger version.

Backup Curta

Curt Herzstark and his Pocket Calculator CURTA.

A good article from backup magazine 6/88 page 5-9 and 1/89 page 41-45

This artice was translated by Andries de Man -- Thanks Andries!

CURTA Patent
(click on the picture)

CURTA Patents

I have discovered a total of 16 CURTA patents!

You can also find HTML versions of the patents at Andries de Man's site

Curta Pins

Curta Pins

These pins were made for an annual collectors meeting in Liechtenstein.

Thanks to Skip Godfrey for sending these pins to me.

I'd be real interested to learn if there were any other pins made and if there were more pins I'd like to get a picture to put on the web site. I'd like to know more about the annual meeting... email me with info...

Curta Mechanism

Miniature Machine Performs Engineering Calculations

A really good CURTA article from Product Engineering magazine -- October 1952.

Demo Curta

A Chrome Curta

Here's a picture of a chrome Curta from Stephan Weiss.

According to Reinhold Rehbein, the history says that, a short time before the factory in Lichtenstein was closed, Curtas were made from different spare parts. Almost every old Curta factory machinist has made a variant.

Demo Curta

A Gold Curta

Here's a Gold version that Reinhold Rehbein owns.

Demo Curta

School Curta

Mathematisches Maschinen-Museum im WorldWideWeb

Prof. Karl Kleine found this picture in an article about use of calculators in German schools. Guess what those boys of age 10 to 11 have in their hands???

CURTA Serial Numbers

CURTA Date by Serial Number

CURTA Production Date by Serial Number contains a discussion and two formulas to calculate approximately when your CURTA was made.

Curta Key

CURTA Literature Listing

CURTA Literature Listing is a list of all know CURTA literature compiled by Rick Furr and Skip Godfrey. Please send us copies of your literature if it is different so we can include it.

Your Curta

The CURTA Manual

The CURTA Manual is a transcription of the CURTA Manual titled "Your CURTA Calculator" on one side and "The 4 arithmetical rules" on the other. Pictures are now included.

The same CURTA Operating Manual rendered simultaneously (CURTA ESP) by Andries de Man.

A French CURTA manual translated by Andries de Man.

A second French CURTA manual translated by Andries de Man.

CURTA Articles

The CURTA Articles page is where you will find interesting articles written about the CURTA.

CURTA E-mails

The CURTA E-Mails page is a set of interesting E-mails distributed by Erez Kaplan's Calculating Machines List server.

Ad-Your Personal          Ad-All Purpose


These CURTA Ads were from Scientific American, June 1961 and June 1971 respectively.

Office Machine


CURTA Operation Manuals, Repair Manuals and More

Ernie Jorgenson with Office Machine Americana is now offering copies of two CURTA Repair Manuals (These manuals were formerly offered by Skip Godfrey). The two Service Manuals were obtained by Skip Godfrey from Daniel Lewin in Germany. Daniels a law student and met Curt Herzstark shortly before his death; Herzstark gave him the manuals. With Skips and Daniels permission we are offering photo-reprints of these Service Manuals to anyone who wants them.

Ernie is offering a total of 7 documents related to the Curta:

CU1. Service-Handbuch For Curta Rechenmaschine Model II 11 X 8 X 15. This manual is written in German, however it has many 'exploded' detailed service pictures of the Curta Model II. $19.00

CU2. Service-Manual for Curta Calculating Machine Model 1 - 8 X 6 X 11. This manual is written in English. Like CU1 it has many 'exploded' pictures of the Curta Model 1. $19.00

CU3. Curta - The Universal Pocket Size Calculating Machine System C. Herzstark. This is a manual that explains the features of the Curta. Has a number of very nice pictures. We assume that this piece was used to market the Curta. $6.00

CU4. Instructions For The Use Of The Curta - Size 1: 8 X 6 X 11. This is the operators manual that was included with a new Curta. Written in English. $16.00

CU5. Computing Example For The "Curta Calculating Machine." Contains pages of practical examples for this fine machines. In English or French. $17.00

CU6. Rechenbeispiele fur die Curta Rechenmaschine $15.00

CU7. Die CURTA und ihr Erfinder Curt Herzstart (The Curta and It’s Inventor) This is a wonderful piece printed in German. Lots of photos. Circa 1988. $8.00

Please make checks available to:

Please e-mail or send us your snail mail and we will send you our FREE catalog of photo-reprinted old office machine manuals.

Office Machine Americana
Ernie Jorgenson with Office Machine Americana P.O. Box 1161
Lewiston, Idaho 83501 USA 1-208-746-8325 1-208-798-0416 (fax)

"Any questions, please email (Ernie Jorgenson) at"


Jack Christensen repairs CURTA calculators. I've known Jack for many years and can highly recommend him.

Here are a few questions I asked Jack:

What do you charge to clean a Curta?

Typically $85 to $115, depending on the work involved. More often than not, the upper carriage needs a complete disassembly, whereas the main body can be cleaned without a complete disassembly. If the main body needs to be completely disassembled, something is usually bent, out of adjustment, or broken.

What do you charge when repairing a Curta?

I charge $65 per hour of my time. It seems my hours are about 90 minutes long, however, because I rarely finish in the time I originally quoted. Extended repair time is absorbed by me.

What spare parts do you have? Are they expensive?

I actually have many hundreds of new original Curta parts. Most are for inside the instrument, though. I use them when I do general cleaning and repairs. Outer body pieces, replacement cannisters, and external parts that are easily damaged or broken due to abuse are not generally available, although I do occasionally locate some these items. Sometimes I have to fabricate a part, or repair an item as best I can. Obviously, this takes time, and the cost is high.

Parts costs are charged as the traffic will bear. I usually try to be blunt about this to the Curta owner, often telling them that a severely damaged unit is best sold as a "parts Curta". Unfortunately, I've sometimes had to tell this to someone who wanted to repair a Curta looked upon as an heirloom. What to them appears to be a minor issue actually turns out to be a major problem (e.g., a crank handle tilted downward is due to a broken main shaft).

I think the most I ever charged for a repair was about $375. There were many severe problems with the unit. Generally, when the price gets to be above $175 most people simply decide to keep the damaged Curta as a memento.

Can you replace a clearing ring? What costs are involved?

The plastic clearing rings are easy to install. I have several new ones, but I typically do not sell them separately as a spare part. Rather, I install them during a general cleaning and repair.

Metal rings are more difficult to replace. As with the plastic clearing rings, I will only install a metal clearing ring during a general cleaning and repair. It takes a special tool to properly swage the rivet in place. [Editor's note: Very old Type I clearing rings were held on with a screw and nut. The nut was also crimped to the screw threads.] I used all the new metal clearing rings I had about five years ago, but I do have a few used ones that were removed from other damaged Curtas. I have these for both the Type I and the Type II. The original rivets needed to re-attach the clearing ring are hard to come by, but I do have a few of those, too.

Jack's company, Timewise also manufactures a line of rally equipment for TSD competition. The units include TSD computers for running in a Computer Class, units designed for Odo Class competition, and competition and checkpoint clocks. Jack can be contacted for special-order equipment or particular modifications desired for Timewise equipment. Jack also repairs older Zeron equipment. A wide selection of sending units are available.

Jack Christensen
32 Old barn Road
Hawthorn Woods, Illinois 60047
(847) 550-5052

CBI Logo CBI Header

An Interview Of CURT HERZSTARK From 1987

This is a wonderful document. A must have for all CURTA enthusiasts! -Rick-

It can be purchased through e-mail (they snail mail a bill to you) for $13.00.
I just imported it into M/S Word (Arial 12pt) and it's about 56 pages long.

Curt Herzstark, interview by Erwin Tomash, audio tape(s) and transcripts, Nendeln, Liechtenstein, 10 September 1987, OH 140.

* Transcript available in English or German for purchase from the Charles Babbage Institute on paper, computer disk, or by e-mail transfer.

Herzstark, an Austrian inventor and manufacturer of calculators, describes the development of the Austrian Calculating Machine Manufacturing Company (Rechenmaschinefabrik der Austria Erstanden Compagnie) and his subsequent work in the industry. The company, founded in Vienna by his father, Samuel Herzstark, in 1905, introduced the first electrically-driven calculator based on improved designs of the Thomas Arithmometer. Herzstark describes the disruption of the industry during World War I, his involvement with the company after the war, competition with American companies, and his first invention, a mechanical memory for holding subtotals, which appeared in 1928. Herzstark managed the company in 1930 and began work on his own design for a hand-held calculator. With the Anschluss of 1938, the company was again converted to war production, and produced custom gauges for German tanks. Herzstark, a Jew, was able to avoid arrest until 1943, when he was sent to Buchenwald concentration camp and worked as a technician. He recounts his arrest and internment, and how he completed the design of the CURTA hand-held calculator, a prototype of which was produced in Weimar, Germany, by Rheinmetallwerke at the end of the war. The Prince of Liechtenstein bought the design and the calculator was initially manufactured by the CURTA division of Contina AG of Liechtenstein. It was produced until 1972, when the electronic calculator forced it from the market.

Charles Babbage Institute at University of Minnesota
Web page:
Order: The Curt Herzstark Transcripts by Erwin Tomash (OH 140)
Specify: Format: ASCII Text, WordPerfect
Media: Copies, floppy, e-mail
Language: English, German
Supply your snail mail address

CBI can provide: paper copies of the transcript for $0.25 per page;
text file of the transcript in WordPerfect 5.1, 6.0, 6.1,
or ASCII for $10 per disk used plus $3 per oral history;
ASCII text file transfer of the transcript by e-mail for
$10 per order plus $3 per oral history.


Swiss, 1993. It shows a technician assembling the CURTA!!!
It's about 20 minutes, with nothing else, just this.
(Good video quality) Stefan Beck, fax + 41 1 950 55 92.

April 25, 1997 -- Skip Godfrey got a reply to his fax to Stefan Beck.
The video is $80.00, including shipping, and he suggested sending cash and sending it as a registered letter (A bank draft in Deutschmarks cost $15.00).

The Curta Calculator by Jim Bianchi

Curta Mechanical Calculator as used in TSD rallying by Jim Bianchi
(as published in rallye magazine, March 1976)

Links to other CURTA Calculator pages:

The Calculator Reference by
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