The slide rule, invented by William Oughtred in 1622, consists of two divided scales, one fixed and one movable, and a sliding window called a cursor. Slide rules were the primary tool for performing multiplication, division and other scientific functions up through the 1960s and the development of the electronic calculator.

There are straight, circular and cylindrical slide rules, all collectible. Major manufacturers included Keuffel and Esser, Pickett, Gilson, Dietzgen, Post (which became Teledyne), Faber-Castell, Aristo, and others. Early slide rules were made of wood and celluloid, while later ones tended to be plastic or metal.

The rarest slide rules are 19th Century hand-engraved instruments such as Palmers Computing Scale (a circular model), first published in 1843, or the cylindrical ‘Thacher’s Patent Calculating Instrument’ slide rules produced by Keuffel and Esser Co in the 1880s. These can run close to $1,000 in good condition.

Whatever you do, be sure any slide rule you buy is fully intact and working, as finding replacement parts for a specific model (especially the cursor) can be next to impossible.

Best of the Web (“Hall of Fame”)

Slide Rule Museum

Slide Rule Museum

Mike Konshak's amazing antique slide rule reference site 'dedicated to students and engineers of the past and prese… [read review or visit site]

Early Office Museum

Early Office Museum

This site showcases pre-1920 office antiques, including paperweights, writing ink, paper fasteners, seal pressers, … [read review or visit site]

Clubs & Associations

Discussion Forums

Most watched eBay auctions    

1950s Slide Rule Leadholder Makeba Ultra Rare Original Vintage Unusual PencilRare Pickett Georgia Iron Works Co. Hydraulic Slide Rule With Leather Case Universal Circular Slide Rule Plastic Cup 4" Tall Small Slide Rule Keuffel & Esser N-4081-5 Log Log Decitrig Duplex Slide RuleVintage New Teledyne Post 10" Versalog Ii 1460 Slide Rule W/case & Manual NosLamar Electronics Cp-223c/um Humidity And Temp Circular Slide Rule / CalculatorAlfa Romeo Special Tool C 60168 Valve Clearance Slide Rule Feeler GaugeCursor For Hemmi Large Duplex Slide Rule 255, 256, 257, 259, 260, 269, Etc. New.Pickett 4 Foot Slide Rule Classroom Demonstration ModelNew In Box Keuffel & Esser 68-1200 Log Log Duplex Decitrig Slide Rule & SheathPickett Slide Rule Model N4-es Dual Base Speed Rule, All Metal 1959, Leather CasKeuffel & Esser Log Log Duplex Vector Slide Rule With Leather Case & Box 68 1434Vintage 1973 Texas Instruments Ti Slide Rule Calculator Sr-50 No Power CordVintage Circular Fullerton Acudial No. 1458 Slide Rule Made In Tokyo, JapanAntique 1911 K & E Co. Slide Rule Magnifying Glass Original Box Rare Old(#97)Pickett Model N600-es Slide Rule Engineering W Leather Case Vintage Log SynchroVintage Swank Engineering Slide Rule Scale Tie Clip Working Parts Unique!Vintage 1961 Keuffel & Esser 68 1100 K&e Slide Rule & Leather Case Deci-lonVintage H Chapin #73 Boxwood & Brass 4 Fold Folding Rule Caliper Slide 12" RulerVintage Pickett N3-es Slide Rule With Case Vintage-german-top Quality 15 Inch Slide Rule In Original Case-vgc-circa 1950'sSlide Rule, Pickett Dial-rule CircularVintage L.s.s. Co. 6 In. Rule With Finger Slide Free Ship U.s.Sama & Etanieference Tables And Circular Slide RuleVintage German Aristo Rietz Nr.89 Slide Rule Calculator Original Box Case RarePost 1460 Versalog Slide Rule With Leather Case & Mystic Stik (thomas H. Sires)3 Small Old Hand Tools: "spoke" Shave, Slide Rule, Lufkin "no 171" Fold. Ruler80's Vintage Engineer Foil Slide Rule Lot Rotring Faber Castell Typometer & MoreVintage U.s. Army Air Forces Circular Slide Rule Military Pickett Model 103 Es Circular Slide Rule W/ Leather Case, Mark Up CalculatorDietzgen 1780-30w Indicator Glass For Slide Rule 1731, 1732, 1733, 1735Slide Rule Tie Bar Great For The Geek Gevaert Repro Calculating Disc For Photomechanical Processes Vintage Slide RuleSlide Rule Frederick Post Co. Made Occupied Japan W/ Leather Case 12 InchDietzgen Slide Rule Model 1765f, (circa 1925 Antique).Simplex Vintage Clarinet Fingering Slide Rule, Copyrighted 1945 By Alton A BrandPocket Slide Rule Flow Calculator ScovillPickett Model N 500-t Hi Log Log Slide Rule With Leather Case1978 Slide Rule & Original CaseAntique Dietzgen Phillips Slide Rule & Partial BoxVintage Fmc Technologies Slide Rule In Leather Case From Harvard UniversityVintage Metal Pickett Model N903-es Slide Rule With How To Use BookVintage Slide Rule Post 1444k Hemmi With Leather Case The Frederick Post Co.Post Versatrig Slide Rule Instructions Manual Frederick Post Co. 1962 1968Vintage Texas Instruments Ti-30 Slide-rule Calculator - Red Led - 1970's Vintage Goren Point Count Bidding Wheel - Circular Slide Rule For BridgePickett Slide Rule W CasePocket Slide Rule Calculator Timken BearingRare A.w. Faber Castell Electro 1/98 Germany Military Artillery Slide Rule Case Faber Castell 52/82 D-stab Duplex Slide RuleExcellent Rare 4153-1c Ke Keuffel & Esser Slide Rule Leather Holster Orginal Box1939 Keuffel & Esser Co. Slide Rule With Leather Case 4080 With User ManualXmas - 1948 Business & Slide Rule Pub Pickell & Eckel Complete PackageVintage Prestolog Profit & Discount Calculator Circular Slide Rule 1935 Gospel Slide Rule The Haworth Publishing Co. 1946Texas Instruments Ti-30 Electronic Slide Rule Calculator W/ Owner's ManualVintage Pickett Microline 160 5" Slide Rule With Black Slip Case1950s Sterling Brand Slide Rule Operating Instruction Sheet Complete CourseVintage Lawernce Engineering Service Slide Rule Original Box