My very own digital pepper-mill

You know those people who gloat insufferably about how they were in a junk shop in Chickenmilk, Wisconsin, and they found a 1933 Leica or Amazing Fantasy #15 or something for $5, and aren't they clever?

Curta calculator

Well, I scored myself a Curta calculator for forty Australian dollars.

And yes, it was in a junk store, next to the usual random collection of broken cameras and mildewed binoculars.

(When the junk shop owner names a price and you immediately smile broadly and say "Sold!", they know they've screwed up.)

Mine is not an incredibly collectable Curta. It's a Type I with serial number 67087, which makes it an early 1967 unit, with plastic crank and storage case but (slightly unusually, I think) a metal "clearing ring".

Unfortunately, the actual finger-loop part of the clearing ring - the part that adds an element of hand-grenade-ness to the otherwise pepper-grinder-ish look of all Curtas - is broken off...

Curta calculator fisheye

...perhaps because it sticks out when you don't swing it into the stowed position.

And there's no manual either. But it's still easy to twirl the top around to clear the readings, and everything else (including the carrying case) is in excellent condition. It's in perfect working order and clean as a whistle.

Intact Curtas regularly go on eBay for $US700 or more - they're somewhere between slide adders and Fuller Calculators on the mechanical-calculator-collector expense scale (I don't think Enigma machines really count).

So I reckon this still has to be a $US500 item, at least.

(I'm not itching to sell it, but if you're willing to pay top dollar, especially if you're in Australia, let me know.)

The actual practical value of a Curta calculator today, as opposed to its collectible value, closely approaches zero. It's not actually very difficult to use a Curta - for basic calculations, at least. But, like books of logarithms, Curtas have been made about as completely obsolete as is possible by electronic calculators.

Pretty much any electronic computer at all is hilariously superior to the finest hand-cranked calculator ever made. You have to try quite hard to make electronic calculation more obscure than mechanical.

The standard slide rule and its various specialised derivatives still have a place today as an inexpensive and durable rapid estimation tool. But Curtas were never cheap, aren't very tough, and don't let you quickly eyeball a multiplication or logarithm. Don't even ask what you have to do to calculate a square root.

This functional omission is at least partly by design, of course. People whose needs were already served by a $5 slipstick certainly weren't going to spend $US850 in today's money on a Curta.

I could go on, but there's little I could say about Curtas that Clifford Stoll didn't say in his 2004 Scientific American piece about them. Find plenty more resources at and

(Original PDF here; it's one of those weird ones that looks like crummy scans overlaid by what looks like OCRed text, which you still can't search. Does anybody know what the deal is with such files?)

11 Responses to “My very own digital pepper-mill”

  1. Squire Says:

    There is an interesting "history of computing" from Brian Beckman, including him using a Curta to do a simple calculation at Brian Beckman: A Brief History of Computing. I could listen to Beckman talk - about anything - all day. He's fascinating. There are other Channel 9 videos with him I would encourage you to watch, you can find those by clicking the Brian+Beckman "Tag" (I found the game physics video particularly interesting).

    By the way, great deal on the purchase. I wish I could find junk store owners that uninformed.

  2. Noodles Says:

    I originally found out about Curta calculators while reading William Gibson's Pattern Recognition (an excellent book by the way) and have ever since wanted one. After talking about them with my father it turns out he had seen them advertised long ago (yes, in a rally magazine of the time) but had never bought one (and of course now wants one too, but the prices are hideous as you know). Excellent score finding one in a junk shop for $40! *envy*

  3. Mick Says:

    That brings back memories, as an engineering draftsman in the '70s I used to use a Curta. I remember a rep trying to sell us one of the amazing new electronic calculators and we had a competition to see which was faster. Surprisingly there was not a lot of difference in speed for an experienced Curta operator doing basic calculations.

  4. Jax184 Says:

    Oh hell, I had just managed to forget about my burning desire to find one of these, and now you've reminded me...
    If anyone has one in the Vancouver area of Canada and would like to sell it for far less than it's worth, be sure to let me know.

    Anyway, I thought your readers might like a better idea of how this thing's used.

    This video shows the basic operations rather well, and this simulator will let the less fortunate out there to try a few calculations themselves.

  5. RichVR Says:

    Just wanted to say that your photos are always excellent. But the shots on this article stand out. Doing anything different this time around?

  6. Daniel Rutter Says:

    I took a lot more pictures this time, since this is such a pretty object and worthy of more time than mouldy Diet Coke :-). I've got an imaging-related post coming up for which I'll use the Curta pics as examples, with wallpaper images.

    The second picture, by the way, was taken with my Peleng fisheye, using the super-close-focus trick where you unscrew the lens a bit from its mount adapter. The lens was pretty much touching the top of the calculator :-).

  7. Stark Says:

    Ohhh...I haven't thought about a Curta in years!

    I once was heartbroken over a Curta. When I was a teen (late 80's) I had an elderly neighbour lady with 3 young grandkids (ages of maybe 6-10 at the time) who were around every weekend. One weekend I was out mowing the lawn and noticed the kids were tossing around an odd looking item... which I suddenly realized was a Curta. Just about then the oldest kid yelled "Grenade" and lobbed the poor, doomed, Curta toward his younger brothers... who were standing in the road. Curta's do not respond well to hitting pavement from a height. I just about cried. I did however get a good look at the mangled workings of a Curta - which I had only read about to this point. I went over and spoke to the grandmother and she said it was a piece of junk that had been one of her deceased husbands "toys". Turns out her husband had been an engineer at Lockheed. She assumed the Curta was worthless and was mortified to find out that the Curta was anyhting but junk. As a plus the old lady gave me a box of her husbands old engineering stuff - a few texts and several well worn but obviously beloved slide rules in their cases along with the case and manual for the Curta. I've still got a couple of the slide rules (the other ones have been gifts to friends over the years) but don't know what happend to the Curta manual and case. It may be in my parents garage... if I find the case I'll send it along to you as I have no use for it and would rather see it in a good home than auctioned off for a few bucks!

  8. Joe Bloggs Says:

    The Curta was too grenade-like for its own good in that instance, apparently ;)

    Dan, what makes you think that pdf was ever OCRed? Looks just like a crummy scan to me through and through.

  9. Daniel Rutter Says:

    It's a crummy scan overlaid by black text that fills in the gaps, more or less - sometimes the overlay barely lines up with the scan at all.

    Look at this bit, for instance:

    Odd PDF

    The printing there is blue; the overlay is black. Paging around the file in Foxit Reader shows you the scan first, then overlays the black text a moment later; I presume Adobe's reader would behave the same way, since the DocuFarm view of the file looks the same, too.

  10. Darrell Says:

    I had never heard of these until I read your post yesterday. I spent much of the day reading about them. Now I am envious of something I didn't even know existed until yesterday. I did find a neat simulator though, so I can at least pretend that I've used one.

  11. olafcurta Says:

    Search for Curta in Wikipedia and look under External Links for YACS -- Yet Another Curta Simulator.
    [Or I could just, you know, link to it here :-). -Dan]
    It is all about a VRML simulator I wrote this year (2008).
    You need to install a VRML viewer.
    A link to the correct viewer is present.
    Once you instll the viewer you can observe the workings of the Curta in 3D.

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