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    

Pickett No. N 3p-t Pocket Slide Rule Synchrolog New Never Used With Box & BooksKeuffel & Esser Co. "k&e" Deci-lon 5 Pocket Slide Rule #68-1130 W/ Leather CaseVery Rare Chem Eng Slide Rule, Post 1491 (hemmi 257) W Case (s431) Free Usa ShipVintage Slide Rule: Unused Picket Pocket 3p-es In Box With Case And ManualsVintage Slide Rule: Pickett Model 6 In Box Statistical Quality Control W/ InsVintage Fearns Circular Slide Rule England Calculator Chart Scientific RulerPickett Slide Rule, Fuller Traffic Rule, Vintage, Leather CasePickett Slide Rule In Case Model N600-esRadiation Slide RuleSun Hemmi 10" Bamboo Slide Rule No. 254w W/ Original Box - Made In JapanVintage Halden Calculex Circular Slide Rule Made In EnglandVintage Slide Rule: Unused In Box, Pickett N4 Es W/ Instructions, Case, In BoxVintage Frederick Post Versalog Slide Rule No. 1416 Engineers Tool Hemmi JapanPickett 1953 Slide Rule Leather Case Manual Original Box #600 Dual Base UnusedKeuffel & Esser Deci-lon 10 Slide Rule & CaseVintage Edmund Scientific Co. 15" Circular Slide RuleVintage Pickett Model 600-es Log Pocket Synchro Scale Slide Rule W/pouchVintage Slide Rule: Unused Versalog 10" # 1460l In Box With Case & Instr BookPickett Dial Rule Circular Slide Rule Vintage In Sealed PackageSun Hemmi Slide Rule Hughes-owens In Leather Case With ManualK&e - Keuffel & Esser - 4100 Stadia Slide Rule W/ Leather Case & Box Vintage Frederick Post Versalog #255 Slide Rule 12" In Leather Case-hemmi JapanLot 2 Sun Hemmi Toshiba Slide Rule With Leather CasesVintage K+e Deci-lon 10 Slide Rule #68-1100 With Leather Case Very Rare Novotni Weight Slide Rule, No. 1373b, Dual Slides, Vg Cond, (s171)Vintage Slide Rule Faber Castell (aw) Pocket SizeVintage Pickett & Eckel Inc. Model 1010-es Engineers Slide Rule W/ Leather Case~ Mint - Copyright 1954 Pickett Valve Slide Rule - Mint & Complete ~ Vintage Keuffel & Esser Duplex Slide Rule 4071 With Magnifier And Leather CaseVintage Concise Model Ctcs-552 Conversion Tables & Circular Slide Rule W BookletVintage Sun Hemmi Bamboo Slide RuleVintage Frederick Post Co. Versalog Slide Rule Model 1460 With Leather Case K&e Deci-lon 10 Slide Rule Keuffel & Esser With Leather Case Nice!!Vintage Pocket Slide Speed Rule Pickett N600-t With Leather CaseOmega No. 151 Bamboo Slide Rule Made In Japan Wow!!!!!!Vintage K&e Keuffel & Esser Slide Rule 4181-3 Leather Case 1947Vintage K&e Keuffel Esser Polyphase Slide Rule 68 1617 Sealed Near Mint In Box Grace Davison Chemical Slide Rule W/ Case Aristo Darmstadt Nr. 867u GermanyVtg Pickett Allmetal Slide Rule 10" Model 1010es Trig Case Instructions Card BoxUs Rb-47h Load Adjuster Slide Rule Airforce Cox & Stevens Electronic ScalesPickett & Eckel Slide Rule Model No 300 B T S C Saddle Leather Case Holster1948-1952 Occupied‭ ‬japan Post Sun Hemi‭ ‬1446‭ ‬bamboo Slide Rule W/case Euc Pickett N803-es Log Log Speed Dual Base Metal Slide Rule. Free Shipping!Pickett - N 515 T Electronics Slide Rule - Cleveland Institute Of Electronics VgVintage Pickett All Metal N-200-es Trig Slide Rule With Original CasePickett & Eckel Deci-point Slide Rule 1945Vintage Foxboro Flow Slide Rule Liquid Steam Gas With Case1947 Slide Rule Keuffel & Esser N4081-3 Reinforced Leather Case ExcellentcondtnPickett No. 120 Slide Rule W/ Case & Instructions Made In UsaNice Vintage 12" Pickett Model N901-t White Simplex Slide Rule Post Student Slide Rule1930s Slide Rule Wood & Cellulose By P I C Electrical CalculatorVintage Slide Rule Us Military Walnut American Blueprint Co. W/ Case Pickett Slide Rule Model N 1010-t Trig 17 Scales K & E N4081 Log Log Duplex Decitrig Slide Rule Manual Keuffel & Esser Co.