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    

Vintage Ollech & Wajs Selectron Computer Slide Rule Aviation No Reserve 1$ NrPickett Model N 3p-es Power Log Exponential Metal Slide Rule And Leather CaseVtg Slide Rule Lot Castell, K&e 4181-1, Versalog 44ca-600, Pickett No 4 Vector +Rare Pickett N-16-es Electronic Slide Rule With Leather CaseVintage K+e Keuffel & Esser Co. Pocket Slide Rule 4181-1 W/ Leather Pocket Case Stanley Sweetheart Sw No. 36 Boxwood Wood Brass 6 Inch 2-fold Caliper Slide RuleVintage Monroe Slide Rule Pencil W/instructions & Use In CaseVntg Pickett & Eckel Synchro Scale Model N600-es Slide Rule W. Orig Leather CasePickett - N 600 T 6" Pocket Log Log Speed Slide RuleDeci-lon Keuffel & Esser Pocket Slide Rule With Manual And Leather CaseEstate Small Pickett Slide Rule In Leather Pocket CasePickett Slide Rule Model 600 With Leather Case 6 Inch Vintage Pickett N200-t Trig All Metal 6 Inch Slide Rule With Leather Case In BoxVintage Boxed & Cased 'descal 315' 195mm Diameter Circular Slide Rule CalculatorFowler 2-sided 'vest Pocket' Circular Slide Rule In CaseVintage Sun Hemmi - Bamboo Slide Rule, Made In Occupied Japan - 1951Vintage Pickett 4-es Slide Rule~vector Hybolic Type Log Log Dual Base Old Used Tools,l.s.starrett Slide Rule/caliper #425 & Brown & Sharpe Square #542Vintage Angle Slide Rule Versa-rule Pat.pend. Dall Drafting Engineer Tool1962-64 Vintage Pickett Eckel Model N4-es Slide Rule With Original Leather CaseVintage Frederick Post Co No 1447 Sun Hemmi Japan Slide Rule Box & InstructionsVtg Czech Logarex 27205 Pocket Slide Rule Calculator Calculating Ruler +red CaseVintage Drafting Tool Aristo Slide Rule Scholar #803, Germany (ref.# 4754) Russian Circular Slide Rule (model Kl-1) 1960's. UssrFaber-castell367 105 Year Old Slide Rule With Rare Decimal Tracking Curser BoxedVtg F5100 Radiation Slide Rule Order Form-mfg A.g. Thornton, England-free Ship Pickett N4-es Vector Hyperbolic Dual Base Log Log Slide Rule + Case +belt StrapVintage Crichlow Circular M1 Slide Rule Faber Castell Slide Rule Model 52/82 Mechanical Ruler W/case Germany Vintage Faber-castell Slide Rule - With Case & InstructionPen Holder Universal Circle Metric Converter Circular Slide Rule W/ InstrictionsVintage Circular Slide Rule Rca Pocket Slide RuleThe Dx Edge By Xantek, Inc - Gray Line Slide Rule (free Shipping)K & E Keuffel & Esser Co Slide Rule With Leather CaseVintage Aristo-darmstadt Slide Rule Dennert & Pape Hamburg #867u W. Leather CaseRare Vintage Reed-o-graph Teacher Calculator - 9"circular Slide Rule, Hard Cover Lot Of Kennametal Calculators & Book,tad 71 Catalog,data Books, Trig Slide RuleK & E Keuffel Esser 7" Slide Rule 4181-1 W/leather Case.Vintage 1965 Ge General Electric Broad-band Circuit Slide Rule Calculator Euc!Vintage Lufkin #014 Boxwood Carpenter's Rule - Brass Caliper SlideKeuffel & Esser Slide Rule 4081-3 Log Log Duplex Deceit Rig Dated 1947Post Versalog #1460 Slide Rule - W/ Case, Manual, +Vintage 1930s Slide Rule / Chart: Lennox Aire-flow Heat Loss Calculator, HvacVintage Triangulator Slide Rule Type Tool - Makes Trigonometry Easy W/ Inst.Vintage Slide Rule Nestler Darmstadt D 0121 Vintage 1930s Slide Rule / Chart: Lennox Engineering Calculator, HvacVintage Junk Drawer Lot-knives, Token, Slide Rule, Sign & Openers -25+ PiecesVintage Keuffel & Esser Slide Rule (polyphase) Neles Ventil-rechenschieber Valve Slide Rule, Instructions & Case 1977Vintage 1930s Slide Rule / Chart & Case: Lennox Aire-flo Heat Loss And Fuel CalcVintage Pickett Model N 800 T Log Log Metal Slide Rule And CaseFaber-castell 360 Slide Rule November 1932 In Boxwood With CaseVintage Unbrako Slide Rule Socket Screw Calculator By Standard Pressed Steel Co Old Slide Rule Faber Castell 4/54 Laminated Wood Ex. Cond. 580mm Long GermanyVtg Czech Logarex 27602-ii Exponent Slide Rule Calculator Logarithmic Ruler&case4" General Industrial Co. Calculator Circular Slide Rule - Engineer Math ScienceVintage K & E Slide Rule 4080-3 W/ Original CaseColumbia Research Lab Noise Exposure Limit Calculator Circular Slide RuleVintage 1930s Slide Rule / Chart: Barber-coleman Uni-fin Grilles Registers, HvacVintage Concise Circular Slide Rule American Standard New In Plastic