N gauge trains


How Small Is N Scale Railroading?
N Scale Sizing Explained

Article by Tony Neilson

N scale railroading is becoming increasingly popular, but the various railroading terms and sizings confuses many who are just getting started in the hobby. Even a lot of highly experienced railroaders get a little baffled when trying to decide the correct sizing for N scale scenery and structures. Fortunately the trains are standard so you just have to look on the box to see what scale you are buying. The following is a guide to sizing:

1. With track, the distance between the rails is measured. N-scale is 9mm or if you are working in imperial measurements, it is the same as 5/16 inch between the rails. By comparison, HO-scale is 5/8 inch between the rails.

2. With locomotives, an N scale diesel engine is approximately 4 inches in length. An HO engine is double that at about 8 inches long.

3. With freight cars, a typical N-scale freight car is approximately 3 1/2 inches long. By comparison, an HO scale car measures about 7 inches long. In both N scale and HO, the passenger cars are usually much longer.

4. With buildings, a typical N-scale house door is approximately 1/2 inch in height. An HO-scale door measures twice that at 1 inch tall. The doors for industrial buildings are usually higher.

5. Figures of people on a layout need to be a bit shorter than the door sizes mentioned above.

6. With automobiles, a typical N-scale vehicle is just over 1 inch in length. Again, a HO automobile is about double that at 2 inches long.

7. With telegraph poles a typical N-scale pole is approximately 3 inches tall. In HO the pole would be around 6 inches tall.

The following chart is a handy reference as it shows the scaled down proportions in relation to the real size railroads and the minimum operating radius for various model train scales.




to prototype 

Track gauge 



Length of 50' 

boxcar approx. 



.256"  6.5mm 



























Model Train Resources

N scale book

Getting Started In
N Scale Model Railroading

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N scale Track Plans

Space Saving
From Plan To Performance

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Model Railroading Rail Weights and Codes Explained

There is one other measurement for track that is important. On a real railroad, the actual rails are rated by their weight per yard, which loosely translates to how the rail is to be used. Heavier rails will be used on high speed main line areas, where a lighter rail will often be used in a lower speed or less heavily traveled siding or yard area. Real rails typically have a rail profile height somewhere between slightly under five and slightly over seven inches, depending on the railroad and the standard that it uses. If we were to model the exact rail profile in N-scale, the height of each rail should be between about .031 and .043 inches.

There’s no ‘weight’ measurement in model railroading, but there is a ‘code’ description. The code of the rail refers to the actual rail height in thousandths of an inch above the tie. In N-gauge track, you will see Code 40, 55, 65, 70 and 80 which correspond to .040, .055, .065, .070, and .080 inches tall. You can see that the only rail code that matches actual real world railroads would be code 40. However, this poses a problem that is not unique to N scale railroading.

It’s important in both real railroading and modeling for the trains to remain on the tracks. Modern prototypical railroad cars have wheels that have a rim, or flange that holds the wheel on the rails. Modern cars are also heavy, and the combination of the flange and the weight of the car generally keeps the car on the track. In modeling, the wheel sets also have a flange, but the weight of the car is not proportional to the weight of the real thing. To compensate and keep our small trains on the tracks, the flanges on the wheels are much larger than scale. This is where the rail height comes into play. A code 40 or 55 rail may cause the flanges on some cars, particularly older ones, to ride up over the ties as the car moves, promoting rather than reducing derailment.

There are replacement trucks and wheel sets available for most rolling stock, but the wheels of locomotives are not generally easily replaced. Some modelers have reported success in machining their locomotive flanges to a smaller diameter, but this is a very advanced modeling technique that also requires specials tools and skills. A much easier solution is to use a larger code rail and try to divert the viewer’s attention from the inaccurate proportion.

Code 55 and code 80 rails are the most commonly seen layout standards. Both come in fixed rail and flextrack products. Manufacturers such as Peco, Shinohara, Atlas, and Micro-Engineering provide a complete range of products for mainline track as well as turnouts, crossovers, and other special arrangements.

It is possible to mix manufacturers on a layout, but careful attention has to be paid to the transition between different types and codes of track. At the very least, some shimming will be required to match the railheads precisely enough to prevent derailing. Mixing products is not a good idea for the beginner, however, and it would be wise for you to build a layout or two with homogeneous products before trying to mix and match.

Like other scales, it is possible to hand lay N scale track. If you are a beginner or have poor eyesight and hand-eye coordination, hand laying may not be for you. If it seems attractive, try creating a small diorama with hand laid track before committing to a substantial layout project. There are tools and jigs available from most model railroading hobby suppliers that will help the process, but it is work intensive to say the least. The up side is that it can be marvelously realistic if done well!

Now that the gauge-scale issue should be clear, N-scale will be the convention used for the remainder of this piece. However, before we move on to that, it is worth quickly explaining another point that confuses many who are new to the hobby.

Enjoy your N scale railroading, and get the two books shown at the top of this page. You'll find then really helpful.