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    

Lionel 1954-56 Southern F-3 Powered A Unit ~gorgeous Condition!~Oriental Limited Brass O Scale 2-rail Emd Gp-7 1500hp Diesel Mint In The BoxAmerican Flyer Pre-war "o" Gauge "overland Flyer Set" Very Early-cute-beautiful!Original Lionel # 6816 Flatcar W/ Allis Chalmers Tractor Dozer +box (dakotapaul)Lionel Postwar Cp Super O 2296w 2373 F3 4 Car Pass SetNice! Lionel 226e Prewar Locomotive W/ 2226w Tender No Reserve (dakotapaul)Original Lionel 1578s Passenger Set From 1957 In Ob - No ReserveLionel Post-war 1947-49 Tender Only 2426w Goes With Berkshire 726 $1 No ResMth 30-20096-1 Lackawanna 853 Fm Train Master Diesel Engine W/proto-sound 3.0O Gauge Mth Union Pacific Sd40-2 Non Powered Diesel Locomotive #3834, Used Gb JaExtremely Rare Psc Precision Scale Brass 2-rail O Scale D&rgw L-131 2-8-8-2 MintOriginal Lionel 2234w Empty Santa Fe F3 Passenger Set Box From 1954 - No ReserveRare Brass Overland Omi O Scale 2-rail Northern Pacific A-4 4-8-4 Loco MintinboxLionel 11341 Military Set W/ 6407 Flatcar & Rocket In Set Box, Rare SetLionel 1954-55 Southern F-3 2356c "b" Unit W/ob ~gorgeous Condition!~Lionel 6-18284 O Csx Dash-9 Diesel Locomotive With Tmcc Railsounds C-8Mth Premier O Scale 20-2459-1 Amtrak Ps 2.0 Genesis Diesel Locomotive #811 C-8Lionel Ives Transition 257 Steam Locomotive And 257t TenderLionel Post-war 1958 New Haven Alco Diesel Aa Units 209 $1 No ReserveO Gauge Lionel Up Gp-35 Non Powered Diesel Locomotive #760, Used Gb JaOriginal Lionel 456 Coal Ramp Ob - Outstanding - No ReserveMth Premier O 20-5527-1 Pennsylvania #7 Prr Ps 2.0 Ff-2 Electric Locomotive C-8Lionel Trains Rare Zw Transformer Postwar W Original Box 275 Watts Big Boy TrainBing Pre-war "o" Gauge Schlitz Beer Car-lithographed-1920's Germany-very Nice!Key Imports Up Big Boy #4000 4-8-8-4 Steam Eng & Tender F/p Test Run Only 2rosPostwar Lionel 726 Berkshire Steam Locomotive & 2426w Whistle Tender~nice Orig!Prewar Lionel Model Steam Train Set 257 Engine Antique Toy Catalog Vintage BoxLionel O-gauge Prewar 263-e Steam Locomotive, Ik17Lionel Prewar Dark Green Passenger Set #93 W/ 152 & 629 630 Cars (dakotapaul)Dai Young Nj Custom Brass "sr&rl" On3 0-4-4t Steam Unpainted Korea Brass LocoLionel Postwar O Gauge # 2360 Solid Stripe Tuscan Gg-1 No Reserve (dakotapaul)Mth Sp F3 Aba Diesel Set Southern Pacific Daylight Protosound Stuck In NeutralPrecision Scale Company 67022 N Scale Pennsylvania K-4s 4-6-2 Brass Steam LocomoBassett Lowke O Gauge Locomotive Engine And Tender - No 1082 - Lms - 4-4-0 Lionel 6-28087 O Die Cast Tmcc Union Pacific Up Big Boy Auxiliary Aux Tender Lionel Pre-war "o" Gauge #225 Steam Loco & Tender-orig. Boxes-1938-very Nice!Lionel Prewar Set # 148 W/ 261, 257t + 529 530 Passenger Ob Set Box (dakotapaul)20-2307 Mth Premier Burlington F-3 Aba Diesel Set, O Gauge, Vg Cond, W/orig.boxAmerican Flyer 0-scale Pre-war Tinplate "the Comet" Passenger For Parts/restoreScarce Postwar Lionel 3562-1 Black Operating Barrel Car~w/ob & InstructionsMth 30-9101 Sinclair Operating Gas Station/boxVery Rare Key Imports Union Pacific Fef 4-8-4 Northern O Scale 2-rail Mint Museum Quality Brass O Scale 2-rail Westside Rf&p 4-8-4 Very Very Rare Cp/givensSunset 3rd Rail - Np Z-5 Yellowstone 2-8-8-4 - Factory NewRich Yoder Undecorated Ge44ton Phase Iv Center Cab Diesel Engine 2rosScarce Atlas 2-rail Great Northern Sw8 Diesel 6154-1 Mint New In Box O ScaleOriginal Lionel 6805 Atomic Energy Disposal Car In Brick Ob - No ReserveOriginal Lionel 6651 U.s.m.c. Shell Launching Car - No ReserveGem Models Undecorated Brass Prr B6sb 0-6-0 St-504 Steam Engine & Tender 2rosLionel O Scale Train Madison Hardware Operating Boxcar 6-19816 Lionel 2671w Lionel Lines 12 Wheel Whistle Tender In Original Box Vintage Tin Wind Up Hornby O Gauge Railway Great Western Tank Locomotive- Spares7 Running Marx Train Motors, 333, Windup, Hand Car, Steam, Diesel, Engines # 8K-line California Zephyr 21" 10 Passenger CarsLionel 6-81142 Vision Line Pfe Reefers 3 PakLionel Postwar 2331 Virginian Fairbanks-morse Trainmaster Diesel Locomotive Original Lionel 226e Steam Engine W/ 2226w Tender Parts Only- Lionel O-scale F3a Diesel Locomotive-santa FeLionel Prewar 226e/2226w 2-6-4 Steamer With Die-cast Tender - GorgeousA Pre-war American Flyer 1680 Hudson Locomotive & Tender 1623-a, Tested Working

Recent News: O Scale Model Trains

Source: Google News

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

Somerset County Trainmasters celebrate 15th anniversary
MyCentralJersey.com, June 4th

The club also has an expansive collection of O-scale trains, including Thomas & Friends and The Polar Express and a collection of rare and classic trains. Club members will lead How to Build a Model Railroad tutorials tailored toward model railroaders...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

Monmouth Medical Center unveils $20000 train donation
Asbury Park Press, May 1st

This was the scene at Monmouth Medical Center Friday, when a donated model O-scale train layout worth $20,000 made its debut in the pediatric unit. The interactive, 45-square-foot layout features 10 moving accessories and a seven-car Disney World train ...Read more

Model trains a fun hobby
The Garden City Telegram, March 22nd

Brad Nading/TelegramDavid Demers, 4, Hugoton, tries his hand at running a Thomas the Tank Engine “O”-scale train with a remote control Saturday at one of the displays during the Garden City Train Show in the Finney County Fairgrounds exhibition ...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