Frequently Asked Questions about O Scale/O Gauge

Thinking of switching from HO or N to O?

Here’s the scoop!


  1. I used to hear a lot about O Scale in the 1950s; is it still around?
  2. What’s the differencce between O Gauge and O Scale?
  3. O Scale is so big. Do you need an aircraft hanger to have a decent layout?
  4. What kind of track is available? Do I have to handlay everything?
  5. All I see in my hobby shop is 3-Rail stuff from Lionel, Atlas O and Weaver. Is that all that’s available?
  6. I’m a prototype modeler. How accurate is all this 3-Rail stuff? Can I convert it to scale?
  7. Why are O Scale products so hard to find?
  8. What is P48 all about?
  9. Is commercial track available for P48?
  10. What is On30?

I used to hear a lot about O Scale in the 1950s; is it still around?

O Scale is alive and well and still growing. Standard gauge modeling in the traditional 1.25″ (5′) or P48 (finescale) gauges has changed quite a bit from what many refer to as the Golden Era of O Scale modeling of the 1950s. Many new ready-to-run cars and locomotives are now available and more are being introduced regularly. On30, which uses HO Scale track and wheels to represent O Scale 30″ narrow gauge, is perhaps the fastest growing segment of the overall O Scale marketplace right now.
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What is the difference between O Gauge and O Scale?

Technically speaking “gauge” refers to the width between the rails and “scale” refers to the ratio of the model to the real thing, i.e., the prototype. “O Gauge” is 1.25″ between the rails and “O Scale” is a ratio of 1:48, or one-quarter inch to the foot. More commonly “O Gauge” refers to trains that run on 3-rail track and “O Scale” refers to trains that run on 2-rail track.

O Scale is unique in the sense that there are four different ways to model in “standard gauge”.

  • There are two versions of 3-Rail modeling: Nostalgia and 3-Rail Scale. Nostalgia has a toy train aspect to it (think early Lionel from the 1950s as the best example of this category).
  • There is also what is coming to be known as 3-Rail scale. This still uses 3-Rail track but these modelers emphasize scale couplers and even scale wheels
  • In 2-Rail modeling, the gauge of 1-1/4″ is a hold over from the time when O Scale models made their way over from the European continent. In 1/4″ scale this worked out to be a track gauge of five feet. Modelers just lived with this anomaly for decades, although there were attempts to correct the discrepancy, usually by increasing the scale ratio of the models from a 1/4″ to the foot to 17/64″ of an inch to the foot. This never really caught on since it involved scratchbuilding everything.
  • In the 1960s a group of narrow gauge modelers developed a wheel and flange profile based upon the prototype’s AAR standards, so they could operate standard and narrow gauge models on dual gauge track reliably. This become known as 1/4″AAR and did catch on, eventually becoming what we know as P48 today.

If this all sounds confusing, it’s because it is. O Scale is the only one of the popular indoor modeling scales that hasn’t outgrown its toy train roots and influences. But take heart, because much of the equipment made for 3-Rail is suitable for scale or prototype based modeling with a little extra work. So you can have the best of the many worlds O Scale currently offers.
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O Scale is so big. Do you need an aircraft hanger to have a decent layout?

It really depends on what you want to model. If your interests center on modern diesels or big steam engines and long freights, you will clearly need a lot of space, since such locos will need at least 60″ (although 72″ would look even better) curves to look good. Yes, I said 60-72″ curves. In O Scale, curve radius can get to be a big deal by eating up lots of space quickly. If you also want high scenery to track ratios, dense traffic levels and so on, then perhaps staying in a smaller scale is the better choice. Where O Scale excels is in the amount of detailing one can include on a given model. This suggests that a narrow shelf type of layout would be a great choice among many others. By focusing on the track and the immediate surroundings, all of that wonderful detailing can be fully appreciated. You can build a very satisfying O Scale layout with a variety of operational challenges in a modest space.
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What kind of track is available? Do I have to handlay everything?

Atlas O has a line of commercial track and turnouts using Code 148 rail. Commercial flextrack used to be available from the House of Duddy and Old Pullman in a variety of rail sizes (Codes 100, 125, and 148), but both Ed Duddy and Old Pullman have retired from the business.You will, however, still find their track and Old Pullman turnouts at swap meets and on eBay. A new supplier of turnouts is Check out their website for their current offerings.

For most modern types of track you’ll want to stick with code 125 or code 138 rails which represent 100-132 lb rail on the prototype. Handlaying track is certainly an option also, since it gives you the greatest design freedom just as in other scales. Handlaid track in O Scale lends itself to an extraordinary level of detailing since individual tieplates; joint bars and switch details are readily seen and appreciated. Right-O-Way Products is the supplier of choice for these.
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All I see in my hobby shop is 3-Rail stuff from Lionel, MTH, Atlas O and Weaver. Is that all that’s available?

Absolutely not. Some people jokingly refer to O Scale as the underground scale, in that many of the products are only seen at the O Scale meets and shows held around the country. We have a listing of these shows on our website and in the magazine. The main ones are the Chicago March Meet, O Scale West for modelers in the western states, and the O Scale National Convention, typically held in June or July at various locations. The best way to find out about O Scale products is to attend one these shows and get plugged into the network as it were. Most manufacturers also have websites listing their products and availability. Check out our Ad Links page under the Resources menu.
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I’m a prototype modeler. How accurate is all this 3-Rail stuff? Can I convert it to scale?

It depends on the manufacturer. Atlas O, MTH and Weaver have 2-Rail versions of their product lines, with the only difference being the trucks and couplers. You may need to have your hobby dealer order them for you. I’ve found many of Lionel’s and Atlas O’s newer product lines to be spot on for dimensional accuracy. You can easily convert cars to 2-Rail by simply replacing the oversized trucks and couplers with their scale counterparts. The detailing such as grab irons, ladders and the like are also very nicely done in most cases. If it doesn’t meet your requirements, replacing it with finer materials isn’t a problem. At first glance, some of Weaver’s freight cars leave something to be desired with their molded on detailing. However, many of the basic carbodies are very accurately dimensioned. The molded detailing can be easily removed leaving the car as a great foundation for kitbashing or modifying for greater prototype fidelity.

There are also several O scale kit manufacturers that make prototypical kits for rolling stock. Check our Ad Links and the magazine.
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Why are O Scale products so hard to find?

The overall market for O Scale is very small compared to HO or N Scale. In addition, many of the product manufacturers are small time operations; literally someone who is working from their garage or basement in many cases. Due to the niche aspects of the O Scale marketplace, the production runs are often very limited in quantity and once an item is sold out it’s often considered to be gone forever. This is why many O Scale modelers tend to be pack rats in nature.
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What is Proto48 (aka P48) all about?

Proto48 represents prototype modeling standards where the wheel and flange profiles are direct reductions from the AAR prototype standards. P48 also correctly models the track gauge of 4′ 8-1/2″ instead of the more commonly available wide gauge of 5′ which we refer to as Standard O or 1-1/4″ gauge.

People working in P48 do so because they want to faithfully model a given prototype car or locomotive as accurately as possible. Most, but certainly not all, P48 modelers model the Transition Era of the 1940-50s or the early 20th century steam era. Many of the products such as trucks and wheels and rolling stock choices are geared to these eras. Modern era modelers have a tougher road to follow in P48 due primarily to the current lack of accurate P48 roller bearing trucks. It is possible to use the existing sideframes by replacing the wheelsets; however, this is seen by many as a stop-gap solution at best. As with so many things in model railroading, it’s a matter of how much compromise you are willing to accept to model what you want.
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Is commercial track available for P48?

Protocraft has purchased the dies for the House of Duddy P48 flex track and is now offering Code 125 P48 flextrack. Unfortunetly, there are no commercial turnouts for P48 at this time. Nickel silver frog and point castings made to P48 tolerances are available from American Switch and Signal and Right-O-Way in a variety of rail sizes and frog numbers from #6 to #12. Combined with other track details from Right-O-Way Products, they build into some of the most realistic model track you’ll ever see. Irish Tracklayer is producing laser-cut switch templates for both O standard and P48, which makes building turnouts easier.
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What is On30?

On30 is an interesting combination that has been around for many years. It was popularized in the 1970s by authors Dave Frary and Bob Hayden with their many articles about the Maine two-footers in Railroad Model Craftsman magazine. Basically, it uses HO Scale track, wheelsets and locomotive mechanisms as an easy entryway to narrow gauge modeling. HO Scale track in O Scale represents 30″ gauge, a compromise of sorts, as there were very few if any 30″ gauge prototypes. Most narrow gauge railroads in this country were built to a standard of 3′ or even as narrow as 2′.

On30 saw a huge resurgence of interest when Bachmann introduced their ready-to-run line of locomotives and cars. Ready-to-run trainsets with a loco, some cars and track, has grown into a flourishing market of products. Carstens Publications produces a book called The On30 Annual, which features much more information. We have also featured many On30 layouts in OST. There are lots On30 groups and organizations you could look into, both online and off.

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In conclusion

While there is much more to cover, this should get you started. Please feel free to ask questions via e-mail and let us know what we need to cover here that we didn’t.
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