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[edit] What's Your Slide Rule Worth?

The short answer is, of course, what it will bring. Of the rules in my collection, I've paid anywhere from $4 to $130, and haven't noted much of a correlation between price and condition. Nor, since I'm not collecting with any intent to resell, am I really interested in their value. Having said that, there are some guidelines for coming up with a value estimate for your rule.

Slide rules are most valuable if they're in original retail condition, complete with case, original box, instruction manuals and whatever random accessories were in the original package. In this condition, I've seen rules on the market in the range of $50 to $500 dollars depending on condition, scarcity, and random factors having no bearing on the real world.

Lacking the original packaging, a rule's value drops precipitously. In good condition, with case, expect a value in the $5-200 range. Without a case, you'd have to have a very old rule (200-300 years old!) to have any appreciable value.

Even if all you have is a bare rule, the rule has to be in excellent condition. The slide must be present and undamaged, the scales must be straight enough to slide freely and give good calculation, and the rule must be clean. You might then be able to sell it to a collector who can pair it up with an original case or packaging.

Revisiting the "what it will bring" answer, I recommend you check out the online auctions at eBay. Type "Slide rule" in the search box and see if you can find a rule similar in make and condition. http://www.sliderules.info/ is an excellent site that includes analyses of slide rule prices on eBay and other sites.

[edit] How Much Are You Selling That Slide Rule For?

None of the slide rules here are for sale. If you'd like to purchase a slide rule, may I suggest Slide Rule Universe, eBay and garage sales and antique stores in your area.