HO scale model trains are 1/87 the size of real trains and 1/2 the size of O scale model trains (HO stands for "half O"). As with O scale trains, the letter "O" in HO is a misnomer since the designation was initially conceived as a zero to identify trains that were smaller in scale than 1. But the use of the letter O rather than the numeral 0 crept into everyday speech among model-train buffs and remains the standard way to refer to HO scale today.

Though first invented in the 1930s, HO scale model trains didn’t become popular in the U.S. and Europe until the 1950s when the scale was heavily promoted by Märklin, Lionel, Athearn, and others. HO never quite gained acceptance in England, though, where larger 00 scale trains still predominate.

HO has two important benefits over trains of larger sizes. First, an HO scale layout of reasonably ambitious detail and complexity can fit on a table rather than requiring an entire room, as is the case with larger scales. Second, HO trains are less expensive to manufacture than OO, O, and other large-scale trains, which makes them more affordable to collectors and enthusiasts alike.

Most HO scale trains run on two-rail tracks using direct current (DC). Adjusting the voltage delivered to the tracks can increase or decrease the speed of the trains; reversing the polarity causes the trains to roll in reverse. Some manufacturers, notably Märklin, produce HO scale trains that operate on alternating current (AC), which is delivered to the train via a conductive third rail.

The gauge used by the majority of HO scale model trains is a standard HO gauge track that’s roughly proportional to the size of the trains running on top of it. But as with the OO scale trains in England that run on HO gauge tracks, HO scale trains are also made to run on a variety of different gauge tracks, which themselves are scaled-down versions of historical railroad track sizes.

Of these variants, the most common is called HOn3. This code denotes an HO scale train running on a track similar to the 3-foot, narrow gauge tracks used by Rocky Mountain railroad operators in the late 19th century.

One of the most enjoyable aspects of HO for collectors is the opportunity to join a local module club. Members of such clubs build modules of predetermined size; each module has a finite length of track. When members get together at model train exhibitions or in private homes, the modules are linked up and trains are run on the resulting massive layout, which often feels like more than just the sum of its parts.


Best of the Web (“Hall of Fame”)

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]

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]

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

Other Great Reference Sites

Most watched eBay auctions    

Broadway Limited Ho F7-abb At&sf War Bonnet Diesel Locomotive, Dc/dcc SoundAthearn Ttx Railbox Tbox 60' Gunderson Hi-cube Double Plug Door Box Car CAthearn Genesis G69553 Union Pacific Dda40x #6925 W/dcc, Tsunami Sound/boxHo Athearn Genesis 99041 Atsf Santa Fe F-7a/f-7b Diesel Engine Set Dcc No SoundAthearn Ttx Railbox Tbox 60' Gunderson Hi-cube Double Plug Door Box Car BAtlas Master Series Gold 9614 Csx Ge Dash 8-40cw #7845 Ln/boxHo Athearn Genesis 99042 Atsf Santa Fe F-7a/f-7b Diesel Engine Set UnpoweredWalthers 932-37067, -23839, -27034 Freight Car Sets (3) Ln/boxOmi Ho Scale Brass Frisco '4400' 4-8-2 Steam Locomotive & Tender U/p Ob ExcBroadway Limited 4475 Norfolk @ Western N&w #1218 Paragon 3 Smoke Dcc Snd NibHo Broadway Ltd 218 D&rgw Rio Grande #259 H-9d 2-8-2 Steam Engine Dcc/soundBrass Hon3 Three Truck Shay West Side Lumber No. 8Broadway Limited 5083 Union Pacific Big Boy 4-8-8-4 #4023 Sound, Dcc Ready ExAthearn G9122 Ho Union Pacific 4-6-6-4 With Dcc & Sound #3985 NibAtlas 9613 Master Series Gold Csx Ge Dash 8-40cw #7839 W/dcc, Sound Ex/boxBroadway Limited 5182 Ho New York Central Niagra Class S1b 4-8-4 Niagara #6012 WWalthers Milwaukee Road Hiawatha Passenger Coaches (5) Ln/box1983 United Hon3 Brass Mich. - Cal. Lumber Co. Shay # 2 Locomotive ExcellentBroadway Limited 724 Union Pacific Sf A-b-b Diesel Locomotive Set W/dcc & SoundFox Valley Models Ho Milwaukee Road Hiawatha Coaches (5) Ln/boxWalthers Ho Scale Union Pacific Budd Coaches (5) Ln/boxWalthers Classic Heavweight Pennsylvania Rr Coaches (7) Ln/boxWalthers Chicago & North Western Passenger Coaches (8) Ex/boxRub Air Condition Cars Phs Power Van Nswgr Ind-red Built 2nd Hand Ho SilvermazKato Ho 30-9045 Gunderson Maxi Iv 3-unit Well Car Set Ttx #732958Lionel 0864-125 Rutland 104 Boxcar Ho Scale - Lnib - VintageHo Scale Brass Tenshodo? 350? Gn Great Northern X204 Caboose CustomWalthers Atsf Super Chief Passenger Coaches (8) Ln/boxAthearn Set Of 5 Gunderson Maxi 3 Trailer Trail Ho Scale ExcellentKato Ho 30-9048 Gunderson Maxi Iv 3-unit Well Car Set Pacer Stacktrain #6311Rapido 108019 Ho Lrc Coach Via #3305Rapido 108030 Ho Lrc Coach Via UnnumberedWalthers Ho #932-4135 Ttx 72' Centerbeam Flat Car (standard) Road #856962Ho Nib Rapido Via Rail Canada Steam Generator Car #15472Kato Ho 30-9047 Gunderson Maxi Iv 3-unit Well Car Set Pacer Stacktrain #6303Rapido 107007 Ho Lrc Club Car Via #3455Walthers 932-4558, 932-4560 Duluth Missabe & Iron Range Ore Car-taconite VersionHo Scale Overland Models North American Pd3000 Covered HopperRub Air Condition Car Nswgr Rs Dining Car D-ind-red Built 2nd Hand Ho SilvermazWalthers Ho Great Northern Empire Builder Coaches (6) Ln/boxWalthers Ho #932-9570 Union Pacific City Series Acf Baggage Car 5631-5663 SeriesHo Scale Van Hobbies Cnr Reefer CarA768 4 Ho Rapido Missouri Pacific Rr Eagle Streamline Passenger CarsRapido 108031 Ho Lrc Coach Via Blue Test SchemeRapido 107011 Ho Lrc Club Car Via UnnumberedHo Nib Rapido Via Rail Club St. Denis Club Deluxe Car Car # 650 L@@k! Ho Coach Yard Plated Brass Santa Fe El Capitan Lunch Counter Diner Lionel Diesel American Freedom Ho Electric Train Set Rare 1970's 08125 Htf RareHo Scale Bachmann Hawthorne Village Boy Scouts America 100 Yr Scouting Train SetHo Scale Life Like Santa Fe Train Set Mainline Express W/trestle Bridge No. 8750"railway Prototype Cyclopedia No. 2", 96-pages, Soft Cover, Models-photos-dataAthearn - 10 Empty Large Blue 10-1/2" BoxesAtlas Nj Transit Alp45dp And Multilevel Cars - Whole Series!!!Psc Precision Scale Milwaukee Road Ep-3 Quill Electric F/pRapido Wholesale Train Lot Free Shipping All Trains New Old Stock Unused Milwaukee Road Brass Hiawatha 1938 Train-f7 And 6 Cars Custom PaintedHo Scale Bli California Zephyr D&rgw 10-car Lot - Nib - Baggage, Dome, SleepersHo Scale Dcc & Sound Brass Prr Q2 4-4-6-4 Bli Paragon 2068 . New In Unopened BoxRailway Classics Milwaukee Road Skytop Sleeper F/pNyc New York Central Brass Railway Classics Creek Series Observation Car