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    

Orient Rally Skeleton Slide-rule Automatic Sapphire Crystal Rare & DiscontinuedAn Early & Unusual X-ray Slide Rule For Calculating X Ray ExposuresPickett 101-c / Lietz 3077 Circular Slide Rule “dial Rule” CalculatorVintage Pickett N-1010-es Slide Rule 4-footer Demonstration Side Rules R832 Pz Starrett 12" No.4r Grad Combination Slide Rule 4 Pieces/rulesVintage Lockheed Circular Slide Rule And Navigational Compute On Key RingPickett N600-es Log Log Slide RuleVintage Pickett Model N600-t Slide Rule W/ Original Leather Case Made In UsaDietzgen Drafting Surveying Supply Catalog 1931 Slide Rule Transit Table Level +Large Gilson Circular Slide Rule Binary Calculator, Copyright 1931, 1940Sun Hemmi Hemmi's Bamboo 10 Inch Slide Rule With CasePickett Slide Rule Cleveland Institute Of Electronics N-515-t W/ Case Large Vtg Lot Drafting Drawing Instrument Set Slide Rule Charvos Compass ToolBreitling Navitimer Heritage Book 30 Pages + Instructions For Slide Rule 1947 Cheasapeake And Ohio Railway C & O Chessie Passenger Time Table Slide Rule3 Vtg Aviation Flight Computers Pilot Slide Rule An 5834-1 & Cpu-26a/p & B-3Vintage Circular Slide Rule Soviet Russian Ussr 1960-70s No ReserveConcise Sama And Etani Circular Slide Rule 600-st 1969 W Instructions And CaseMechanical Engineers Vintage Working Slide Rule Tie Clasp Marked JetsVtg Concise Circular Slide Rule W/ Case & Instructions For Boeing Sram MissileNeat Copyright 1942 Shure Brothers Reactance Slide Rule W/ InstructionsVintage Halden Calculex Circular Slide Rule Made In EnglandCircular (round) Slide Rule Russian Soviet Vintage Calculator Kl-1 NexcTie Clip Slide Rule Cleaver Brooks Milwaukee 12 WisWwii Ww2 Era Us Army Signal Corps Shure Brothers Reactance Slide Rule KitVintage Versalog Slide Rule Instructions Book-hardcover-1951-very GoodPost Model 1445 Slide Rule Engineering W Cardboard Case Vintage Log Hemmi JapanVintage Concrete Estimator Slide Rule-bay City Material Co.-phone 8366Vintage Keuffel & Esser Polyphase Slide Rule Manual 1938 - K&eIwa Rs 331 Slide Rule. Rare. Unusual Diagonal Scales. Free Shipping!Pickett N-500-es Metal Slide Rule Vintage 1962 W/leather CaseVintage K E Keuffel Esser Co. Wood Slide RuleVintage Pickett Slide Rule Microline 120 W/ Leather Pouch / Case Nice!!Aristo 10132 Baustahlgewebe Slide Rule / Reinforced Concrete Excellent ConditionGreat Quality Vintage "sun" Hemmi Slide Rule Japan