O scale refers to a model railroad train that is 1/48th the size of a real train—in the U.K., O scale trains are generally 1/43rd the size of the real thing while in Europe they are 1/45th as big. Like a real train, O scale model railroad trains run on two-rail tracks. The gauge of those tracks is O, which describes tracks whose rails are 1 ¼ inches apart. Even though O scale model trains frequently run on O gauge tracks, strictly speaking, the two Os have nothing to do with each other.

The letter "O" is actually a misnomer since the designation was initially conceived to identify trains that were smaller in scale than 1, which had been the standard. Since the only number smaller than 1 is 0, that’s how early O scale trains and O gauge tracks were identified. Similarly, HO was originally intended to describe a scale and gauge that is half (H) of zero, but the letter O (pronounced “owe”) crept into everyday use among model train buffs and has remained the way to refer to zero ever since.

Confused? A lot of people are. But for those who are first and foremost focused on O scale, nothing else matters. For these enthusiasts, replicating the detail of a full-scale train in an equally detailed layout is the only goal.

An O scale model train’s tracks, as it turns out, are a key part of creating a sense of realism. When an O scale train is run on three-rail O gauge tracks (the middle rail delivers the power to the locomotive) such as those made by Lionel, the train rides higher off the surface than it would in real life, thus shattering the illusion. Model railroaders who run O scale trains on three-rail tracks are known as hi-railers. It’s not quite a put down, but it isn't really a compliment, either.

Toy manufacturers in the early part of the 20th century originally embraced the O scale so they could offer customers model trains that took up less space than their standard-sized counterparts. Because they were smaller, these trains were also less expensive. At one time or another, Märklin, Lionel, MTH, Williams, Atlas, and Weaver, among others, all offered O scale trains. Fans of brass model trains are also frequently O scale acolytes because the earliest, most collectible brass trains made in postwar Japan were usually O scale.

The smaller scale took off in the 1930s, when affordability trumped most other concerns thanks to the Depression. The scale also benefited from its adoption by industry leader Lionel, which sold two O gauges for its O scale trains. Lionel’s regular O gauge track was the same width as its O-27 gauge track (1 ¼ inch), but the O-27 had a lower profile than regular O, and its thinner rails allowed all but the longest O scale model trains to make tighter turns (a circle of O-27 tracks has a diameter of 27 inches instead of 31).

Today, neither appeal to O scale purists who put accuracy and authenticity above mere convenience. There is even a vocal contingent of two-rail O scale enthusiasts who advocate for the conversion of model trains designed to run on three-rail tracks to model trains that will run on just two. This often requires changing a train’s trucks (the framework for the axles and wheels) as well as a layout’s wiring (from AC to DC), but the lower profile that results makes an O scale model train look a lot less like a toy and more like the real thing.

Best of the Web (“Hall of Fame”)

Airfix Model Railways

Airfix Model Railways

Dave McCarthy's Airfix Model Railway treasure trove is an in-depth archive of the company's plastic railway kits fr… [read review or visit site]

Gateway NMRA

Gateway NMRA

This great reference site for model railroaders, from the Gateway (St. Louis) division of the NMRA (National Model … [read review or visit site]



This site is a treasure trove of HO scale model railroad manufacturer catalogs and other reference information, inv… [read review or visit site]

Postwar Lionel Trains Library

Postwar Lionel Trains Library

Bernie Schulz’s Lionel Trains Library focuses exclusively on postwar Lionel trains and accessories. The site cont… [read review or visit site]

Eric's Trains

Eric's Trains

Eric Siegel's site displays his collection of O-gauge/O-scale trains, tracks, turntables, and other accessories. A … [read review or visit site]

Tech Model Railroad Club of MIT

Tech Model Railroad Club of MIT

MIT's model railroad club, as one might expect, has one of the best websites for learning about how people play wit… [read review or visit site]

Clubs & Associations

Discussion Forums

Other Great Reference Sites

Most watched eBay auctions    

Vintage1960's Lionel Us Navy Diesel Train Set Lot With Boxes! NrLionel 4-4-2 Steam Loco No. 350-e Hiawatha Train Set 882-883-884 Passenger CarsAmerican Flyer Pre-war "o" Gauge Hudson Streamliner Set-1936-original-nice!Postwar Lionel 773 Hudson Steam Locomotive & 773w Nyc Whistle Tender~nice Orig!Original Vintage Lionel Pre War Outfit # 266 With BoxesLionel Postwar 2023 Union Pacific Alco Diesel Engine Locomotive Aa O Gauge TrainVintage Lionel 2037 Locomotive Tender & Additional Cars Px71Lionel 2351 Milwaukee Road Ep-5 .. Almost Wowsers .. ObMth O Scale Emd Sd70ace Bnsf Model Train Locomotive Engine 20-20426-1 Diesel AwO Gauge Lionel Atlantic Coast Line F-3 Aba Diesel Set #342 Working Used Gb JaVintage Lionel Lines Lot Of 5 Passenger Cars 2435 2434 2432 2421 & 2436 Px94Lionel Trains Postwar #2056 Hudson Steam Engine Set W Original Boxes Usa Made Lionel Trains Postwar Rare Erie Diesel Engine Set #2032 Usa Made 1952 0-027 Gage6-11437 Lionel Vision Line Union Pacific 4-8-8-4 Big Boy #4014!O Scale 2-rail Brass Kemtron 2-6-0 Wabash Mogul Steam Locomotive W/wood CaseVintage Lionel 2365 Chesapeake & Ohio C&o Gp-7 Diesel Px67Postwar Lionel 2365 Chesapeake & Ohio Gp-7 Diesel~w/nice Ob & InstructionsVintage Lionel 2328 Burlington Diesel Locomotive Px66Vintage Lionel Lines 2533 Silver Cloud & 2532 Silver Range Passenger Cars Px100Lionel Postwar 2343 Santa Fe F-3 Diesel Engine & Dummy,boxs,instructions,paper Original Lionel 2350 New Haven Ge Ep-5 Rectifier In Ob - No Reserve20-2484-1 Mth Premier U-pacific F-3 Diesel Aba Set, O Gauge, Vg Cond, W/orig.boxPrewar Lionel O Gauge Large Red Tinplate Passenger Car Set No.710 & 710 & 712 Lionel 2600, 2601, 2602 Pre War Passenger Set .. Extra BrightLionel Pre War 600, 601, 602 Passenger Cars .. WowsersVintage Lionel No. 175 Rocket Launcher In Original Box Px47Lionel 6-38075 Lionmaster Union Pacific Big Boy 4-8-8-4 With Original BoxPostwar Lionel 665 4-6-4 Steam Locomotive & 6026w Whistle Tender~w/nice Ob'sO Gauge Train Dorfan / Ives Pre-war Passenger Set All Original Lot Of 6Lionel Pre-war "o" Gauge City Of Denver Streamliner-1936-orig. Boxes-very Nice!Postwar Lionel O No.2143 671 Steam Engine & Freight Set With Rare Lighted TenderBachmann Spectrum Ho 80-ton Three Truck Shay - Painted - Unlettered - BoxedVintage Lionel 6250 Seaboard Diesel Switcher Locomotive Px31Lionel 6-28063 Pennsylvania T-1 4-4-4-4 Duplex Steam Locomotive & Tender Ln/boxLionel 1100 Mickey Mouse Wind-up Handcar Green Base No Reserve (dakotapaul)Mth Tinplate Traditions Prewar Lionel No.840 Industrial Power Station In The BoxVintage Lionel 213 Minneapolis & St Louis With Dummy Unit Px70Prewar O Gauge Leland Detroit Co. Elevated Monorail Passenger SetSunset Models O Scale 2 Rail Brass New York Central K-5 4-6-2 PacificLionel 2332 Pennsylvania Prr Gg-1 Dark Green .. ObMarx Vintage 5 Car Train Set O Scale For Parts Or Repair Lionel 2322 Virginian Fm Trainmaster .black Mold. Ob .. Really NiceLionel Conrail Legacy Scale Sd70mac Diesel Engine Big Blue 81094 O Gauge 6-81140Pre-war American Flyer Burlington Zephyr 9900Lionel Trains Car 6-17433 Bnsf Bathtub Gondola 3 Pack Die Cast O Scale Z678 Rm3 Vintage 0 Gauge Model Railway 3x Locos Rolling Stock Carriages Hornby MeccanoVintage Lionel 226 Boston & Maine Alco Diesel With Power Unit Px97Lionel 6-11208 Lionmaster Big BoyLionel 2349 Northern Pacific Gp-9 Diesel .. Ob .. WowsersToy Stamp & 1920s Ives Wind Up Train Set Good Still WorksPostwar Lionel 6464-450 Great Northern Boxcar~w/nice ObLionel Trains Postwar Coaling Station #497 Usa Made Electric Need Help Accessory Mth 20-80001a Up Big Boy 4-8-8-4 Steam Engine D.a.p Dealer Appreciation Late Prewar Lionel 2814 (type Ii) Orange & Brown Box Car With Original Box 1940High Grade Lionel Postwar Gg-1 Prr No. 2332 5-stripe Loco +box (dakotapaul)Vintage Lionel Train Set Huge Lot Engine Cars Track Signals Controls TransformerPrewar Lionel Tinplate Passenger Cars 6440 6441 Observation Px35Lionel 2530 Large Door Rea Baggage Car .. ObPrecision Scale Company O Scale 2-rail Brass Southern Pacific C-30-1 Caboose ExO Gauge Lionel Atlantic Coast Line 4 Car Aluminum Psgr Set Lightd Used Gb Ja

Recent News: O Scale Model Trains

Source: Google News

All aboard for train show
El Defensor Chieftain, August 19th

Some old toy train sets have become quite valuable and most can be brought back to life for the enjoyment of both big and little kids.” The New Mexico Division of the Toy Train Operating Society will have its modular “O” scale layout set up and running...Read more

Getting out
Ellwood City Ledger, August 19th

Featured will be G scale, O scale and HO scale operating layouts and train-related vendors. A large rail memorabilia auction will begin at 6 p.m. Proceeds benefit the West Pittsburg station restoration project. Interested vendors or information: www...Read more

Evening News and Tribune, August 14th

The Southern Indiana Railroad will be hosting a model train show from 1 to 8 p.m., Friday, Aug. 21, and a model ... There are four layouts scheduled to be on display showing HO scale, N scale, S scale and O scale for the varied interest of everyone...Read more

Spring Creek Model Trains thrives in rural Nebraska
Lincoln Journal Star, June 27th

“When I went down there about three years ago, I was blown away,” said James Wright, a model train enthusiast from Papillion, who manages a YouTube channel -- JLWII2000 -- about model trains. He travels the country for his videos and has featured...Read more

Marion man a finalist in Lionel train competition
McDowell News, June 20th

As part of its 115th anniversary celebration this year, Lionel, LLC, the iconic electric toy train company, will unveil a brand new boxcar featuring an original design. And this O-scale boxcar could feature the winning design created and submitted by a...Read more

Crosslake model train museum displays new exhibits and layouts
Northland Press, May 25th

The members of the museum have also been busy this winter and spring building new layouts and scenery on the O Scale and HO Scale model train layouts. The O Scale now features a coal processing plant, and the Saint Paul Union Depot model has been ...Read more

Model train show rides into Augusta Expo
Staunton News Leader, May 3rd

Seeing them smile ... it makes me happy." There are four different scales for model trains — G scale, which is a 1:22 proportion/scale; O scale, which is 1:48; HO scale, which is half of the O scale at 1:87; and N scale, the smallest size at 1:160...Read more

Railroad Days to be hosted, appropriately enough, at Allen Train Depot
Star Local Media, March 11th

Local Allen resident Stan Schwartz is an active Dallas-Fort Worth O Scale Club member and is organizing the Allen exhibit. Schwartz has been collecting model trains for over 60 years. In 1952, he bought his first Model Railroader magazine and continues ...Read more