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    

The Mechanical Engineer Pocket Calculator Slide Rule Stanley Fuller Calculator Scientific Logarithmic Slide Rule With Manual & BoxAntique / Vintage Rulers Folding Bone Ivorine & Ebonised Slide & Treen Wood RuleVintage Keuffel & Esser (k&e) Log Log Duplex 5" Slide Rule 4181-1 W/leather Case Vintage Pickett Dual Base Log Log All Metal Slide Rule With Box & InstructionsRare Slide Rule Vintage Calculators Lot Of 19 All Work Perfectly!Phil Irving Motorcycle Technicalities Vincent Velocette Norton Iom Slide RuleVintage Pickett Dial Rule Circular Slide Rule 101-cVintage Commodore Model Sr 1400 Slide Rule Calculator WorksVintage Teaching Slide RuleStanley No. 15 Two Foot Two Fold Rule Gunter's Scale Brass SlideWow Large Vintage Working Demonstration Shop Sign Slide Rule Pickett & Eckel 7ftVintage Frederick Post Versalog 1460 Slide Rule And Leather! Amazing Condition!Vintage Post Versalog #1460 Slide Rule In Original CaseVintage Frederick Post Co. Versatrig No. 1450 Slide Rule W/ Leather Case JapanFaber-castell 67/54 R Slide Rule And AddiatorCirca 1960's Circular Slide Rule On A Cigarette Lighter Mib *g*Nos Vintage Hemmi Versalog Geotec Slide Rule W/leather Case Japan **mint**Pocket Slide Rule - Japanese - Sun -hemmiRare Slide Rule!! Circular Binary Slide Rule 1931! Rare MetalVintage Pickett Microline Slide Rule Model 120 With Case Near Mint ConditionFrederick Post Co. Binary Slide RuleVintage Slide Rule Tie Bar Clip Gift Unbranded Gold ToneVintage Concise Circular Slide Rule No. 28 With Plastic CaseVintage Westinghouse Sun Hemmi Post 6" Pocket Slide Rule Made In Japan Sun Hemmi Bamboo Slide Rule No 50 With Box Made In Occupied Japan Circa 1947-49Vintage Sun Frederick Post Slide Rule 1444 W Leather Case & Original BoxBritish Thornton P271 Log Log 10" Sliding Slide Rule Case; Ships From Us;vintageFisher Universal Control Valve Sizing Slide Rule - NewVtg Concise Circular Slide Rule Westennoff And Novick With Instruction ManualSterling Decimal Trig Multi-log Slide Rule Case & Instructions No. 594Vintage Keuffel & Esser # 4081-3 Slide Rule Nice Cond With Original Case Usa New Circular Slide Rule 270 From JapanCircular Slide Rule Keychain U.s. Navy Asw Team S-3a, P-3c Ground Speed IndexRare 1940's Vintage K&e Box Dietzgen Slide Rule Indicator Pat # 2407338Vintage Slide Rule Tie Bar Clip Gift Unbranded Gold Tone1955 Keuffel & Esser Co. Slide Rule Manual #4081 Log Log Duplex Decitrig Vintage Lawrence Engineering Service Peru, Indiana Wood Slide RuleVintage K&e Keuffel & Esser 4081-3 Log Log Duplex Decitrig Slide Rule W/ Case12-inch Graphical Firing Tables Slide Rule - Complete Nov. 1944 Ref: 5028tAcumath No. 1500 Us Miltary Slide Rule & Case EucPicket 902 Slide Rule Kit, Vintage Slide Rule With Instructions N902-k-es, NibVintage Lawrence Engineering Service Wood Slide Rule 8" LongKeuffel & Esser Co. N. Y. Log Log Duplex Decitrig Slide Rule W. Leather Sheath The Log Log Duplex Decitrig Slide Rule Manual - No. 4081 - Keuffel & Esser 1945Vintage Pickett Microline Slide Rule No. # 120 With Leather Case Vtg West Grove Masoneilan Cashco Plumbing Related Slide Rule60's/70'sVintage K & E Keuffel & Esser Co. Ny N4053-3 Slide Rule & Leather Case UsaVintage 6" Wooden Pocket Slide Rule Great ConditionVintage Pickett 500 Slide Rule, How To Use Log Log And Metal CompassVintage Pickett Microline 120 Slide Rule W/case & Instructions