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    

Aristo Studiolog 0969 Slide Rule. Nice!Sun Hemmi No. 154 Slide Rule, Made In Occupied JapanSuperb Vintage K&e Deci- Lon 5,68-1130 Pocket Slide Rule In Box With ManualsK&e Decilon Slide Rule 68 1100 Very Rare, Original Box, Instruction Book - 1966Vintage Rare Pickett Hydraulic Slide Rule By Georgia Iron Works D. W. HaglerPickett N 3-es Power Log Exponential Log Log Dual Base Slide Rule Mint With CaseRare Otis King's Slide Rule Calculator Model K -- A 6441 With Leather Sleeve1956 Usaf Sac Boeing B52-g Stratofortress Circular Slide Rule Flight Computer Pickett Pocket Slide Rule Model N600 Es N 600 W/leather Case & Paper WorkVintage Faber Castell 2/82 N Novo Duplex Slide Rule W/ Case Germany. No Reserve!Collection Of 19 Slide Rule Calculators From 1920's To 1960's And InstructionsVtg~1982 Reliability & Confidence Metal Circular Slide Rule,aga Space Technology Pickett N4-es Slide Rule, Ex Cond, W Case1960's Era Cardboard And Plastic Engineering Slide Rule Type CalculatorsLate Vintage Teledyne Post 44ca-600 (1460) Versalog Slide Rule, August 1972, NmVintage Fowlers Universal Calculator In Case - Round Slide Rule Super !!Picket & Eckel Slide Rule Deci Log Log Vector Model 3 W/vinyl CaseVictorian Milliners Hatter Calliper Slide Hat Makers Rule Ruler T Bradburn SonsDietzgen Microglide Slide Rule G-1734 - Mint_vintageRaphoplex Slide Rule With CaseUnusual Vintage Mens Tie Clip **slide Rule**1948 K+e Slide Rule With Manual And Box No. 4081 Log Applies To No.4181Vintage Antique Folding Stanley Ruler And Engineering Slide Rule In Case U.s.a.Vtg Lot~tobacco Tin Lighter Mining Slide Rule Hot Wheel Red Line Broadhead CokePickett Slide Rule W/leather CaseAristo Studio 0968 Slide Rule.1750-`1790 Brass Sector - From France - Like An Early Slide RuleVintage Keuffel & Esser 22" Slide Rule K & E 4081-5 Log Duplex Decitrig W/ CaseAntique Keuffel & Esser Slide Rule #4031 With Leather Case Pat. June 5, 1900 Vintage K&e Keuffel & Esser 4083-3 Slide Rule W/ Case Usa 1947 Duplex VectorVtg Slide Rule 1460 Versalog Frederic Post Hemmi Bamboo Japan 101200Vintage Dietzgen Phillips Wood Slide Rule 1759bGeneral Dynamics Reliability With Confidence Circular Slide Rule W/ DirectionsVintage Descal Circular Slide Rule Calculator By Blundell Harling Vintage Kueffel & Esser Slide Rule Log Log Duplex W/leather Case K&e 523519Vintage 1947 Keuffel & Esser Slide Rule 1947 With Leather CasePicket Slide Rule W/leather Case Advertising Aar-comm/sig 1967Early Albert Nestler? Slide Rule + CaseSlide Rule Taylor Hygrometer Short & Mason 3805p Relative Humidity Bulbs RarePre 1963 Wood Caliper Brass Inside Outside Slide Rule Bradley Lumber Warren Ark 3 Pcs Slide Rule Russian With Box Vintage Ussr Vintage Keuffel & Esser - 4081-3 - Slide RuleSmall Frederick Post 1441 Slide Rule Sun Hemmi Japan W Magnifier & Leather Case Metric Conversion Scale - English Slide Rule - Todays Army - Vintage 1979Russian Circular Slide Rule (model Kl-1) 1960's. UssrSeger Slide Rule Seldom OfferedRare Soviet Russian Slide Rule ЛСЛД 250-14 1909 Patent Faber Castell Slide Rule Leather CaseOilfield Oilwell Oil Rig Drilling Rig Roughneck Api Flange Slide RuleKeuffel & Esser Slide Rule 4081-3 With Leather CaseK & E, Keuffel & Esser 4081-3 Slide Rule With Leather Case Keuffel & Esser 4081-3 Log Log Duplex Decitrig Slide Rule K&e W/ CaseVintage Pickett N803-es Yellow Slide Rule Sterling 594 Precision Slide RuleAntique Vintage Slide Rule/caliper Hudson Forge Co 3"Pickett Slide Rule With Metric ConverterKeuffel & Esser Log Log Duplex Slide Rule 4080-3 With Leather Case - CrackedVintage Made In Germany Logaritmic Slide Rule System Darmstadt Meissner-fabrikatDietzgen Micromatic Slide Rule Case, Warrenty, Indicator Glass Conversion TableVintage Stanley #36 Boxwood Carpenters' Rule Brass Caliper Slide - Sweetheart Tm