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]

HOseeker.net

HOseeker.net

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    

Lionel "lionel-ives Lines" Clockwork Pass. Train Set, Original, Gorgeous, Rare!!Mth 20-3084-1 Pennsylvania 4-8-2 M-1b Steam Loco W/ps 2.0 Ln/boxLionel Postwar 2360 Pennsylvania Prr Gg-1 Gg1 Electric Engine Vintage 1930's Ives? Engine Trolley O Scale TrainLionel 1957-58 746 Norfolk & Western "j" & 746w W/ob's ~superb Condition!~Lionel Santa Fe No. 208 Set Of Aa Alco Diesel Engines No Reserve (dakotapaul) 0 Scale 2 Rail Usra 2-8-2 By Sunset Models Made By SamhongsaMax Gray "o" Scale Brass Union Pacific #844 Fef-3 4-8-4 Loco & Tender, Nice!Rare Ives Early #113 Passenger Station Full Litho 1910-1912Marx Wm Crooks 4-4-0 Train Set W/ Original BoxLionel 6-28069 Century Club Ii Nyc Niagara 4-8-4 Steam Loco & Tender ExLionel 6-38071 Southern Pacific Ac-12 Cab-forward Locomotive & Tender Ln/boxK-line K2470-8322 New York Central Rs-3 Powered Diesel Ln/boxPrecision Scale Crown Sp Ac-3 Fact Ptd & Ltrd #4085 W/strmline Cab,tro, Ln,ob Lionel 2360 Tuscan Gg-1 Electric Locomotive~w/nice Ob & InstructionsLionel 6-29800 Maintenance Of Way Crane Car W/tmcc Mt/boxEarly American Flyer "chicago" Coach. Edmunds Metzel!Vintage American Flyer O Gauge Royal Blue 556 Locomotive & Tender Tested & RunsLionel 773 Hudson, Circa 1950, With 2426 Tender, Very Nice, With Boxes.1950's Lionel 0 Gauge Diesel 2343 2343c Santa FeLionel 6-18058 773 4-6-4 Cc Hudson Steam Locomotive & Tender W/display Case LnVintage Lionel Santa Fe 2333-20 #2343 Engine & Dummy Set With Original BoxesMth Trains Transformer Z4000 400 Watt-mint Boxed-txPrewar Lionel Ives Lines No. 1651e Electric LocomotiveAntique Lionel 773 Hudson Steam Engine Die-cast Vintage Toy Train Railroad Lionel Trains #213 Lift Bridge 6-14167 New Nrfb O Scale Model Railroad New MintNr Mth Railking 30-1172-0 Jersey Central Blue Comet Pacific Steam Engine MintIves "o" Gauge No. 3253 Electric Locomotive, Cast Iron Frame, Original Paint!!!Lionel 6-51000 O Scale Hiawatha Passenger Train 1988 Limited Edition Set Mm21 RrLionel O Gauge Post War Train Aluminum Passenger Car Set Of 5 #2530+ No Box-txLionel New York Central # 2333 Diesel Engine, Early Model 1949K-line #k3680-9628 Prr Mikado & Tender-pennsylvania-mint Boxed-txLionel No. 2331 Virginian Fm Train Master Blue Yellow No Reserve (dakotapaul) K-line Golden State Aa Unit Diesel Locomotive & 5 Car Passenger Set K2132-01031Marx Trains Diecast New York Central 2-6-4 Steam Train Engine Tender Set PostwarLionel Legacy Control System #990-mint Boxed-tx0 Scale Brass 2 Rail Nyc 4-6-2 Class K-5b By Sunset ModelsLionel O Gauge Post War Train For Repair Engine #736 W/box-txMth Premier 20-3043-1 Pa Rr 4-4-4-4 T-1 Duplex Steam Engine Tlc NeededMth Train Set Southern Pacific Ac-6 Cab Forward Die-cast Steam Loco Engine NewPair Of Powered O Scale Trucks - Possibly Street Car, Trolley, Rdc Car ??Lionel 6-38071 Southern Pacific Ac-12 Cab-forward Locomotive & Tender LnPre War American Flyer 9900 3 Piece Burlington Zephyr StreamlinerVintage Postwar Lionel Train #646 Santa Fe-style Hudson Steam Engine W/boxLionel O Gauge Post War Train New York Central Car #2344c W/box-txMth 20-98361 John Deere Flat Car NibPostwar Lionel Boxcar & Searchlight Car Lot X2758 X3464 X2454 3520 3650Lionel Trains Passenger Car Set Silver Red Letters Summit Clifton Newark Nj LthLionel Santa Fe U36b Diesel Engine No. 8755, No BoxIves 1132 Locomotive & Tender Original Antique Lionel 2344 New York Central F-3 Diesel AaO Scale Mth Amtrak F40ph Diesel Engine W/ps 2.0, Item# 20-2798-1, Ln/ob - De Rare Early Wj Bl Bassett Lowke Steam BoilerLionel O Gauge Post War Train Warbash Engine #2367 W/box-txLionel Chicago North Western Fm Trainmaster Diesel Engine Item# 8056 W. BoxMarx Mar Lines Vintage Walt Disney Mickey Mouse Meteor Tin Train Set Rare Mth Trains Dc-3 Union Pacific Rail Inspection Car Dual Motors Sounds Smoke BoxedLionel O Gauge Post War Train 1960s-boat Transport Car #6416 W/box-txKtm O Scale U-100 Complete Gear Box To Regear Steam Locomotive - NewPrecision Scale Brass Gulf 36’ 10k Acf Insulated Tank Car C/p 2 Rail O Scale

Recent News: O Scale Model Trains

Source: Google News

Crosslake Model Train Club Ready for Summer Visitors
Northland Press, July 7th

The club is currently selling raffle tickets to win a complete 4' by 8' O scale model railroad layout. It's very cool! This raffle will raise money for our operating expenses. Come to the club to view the layout and purchase your tickets. The estimated...Read more