Choosing a Model Railroad Scale & Gauge

This simply means all the dimensions of the full size item (the ‘prototype’) are divided by 87. So 87 models all lined up would be the same length as the prototype. 87 stacked up would equal the height of the prototype.

HO is also known as 3.5mm scale. 3.5mm on the model represents 1 foot (12 inches) on the prototype or full size item. HO scale actually stands for Half O.  HO trains run on a 16.5mm gauge track.

• It’s easy to find accessories and features that are designed for the HO scale
• HO accessories tend to be very affordable

• May be a little too small for very young children to handle effectively
• Requires a little more space than the N scale, so it may not be suitable for people who have very limited amounts of space.

Historically, the reason for this discrepancy appears to be that HO was first introduced in Germany in the 1920’s. Naturally, there was soon demand for similar sized models for the British market. Due to tighter clearances in tunnels, under bridges, in platforms etc., full size British trains are not as tall or wide as those of many other standard gauge railway systems. Therefore there was difficulty fitting the bulky motors of the time into British models made to HO scale. And so they were made slightly larger to overcome this problem. This also made them more visibly compatible, size-wise. Although the scale was larger than HO, the 16.5mm gauge was retained for compatibility.

Today, the scale is too well established to change it. A few manufacturers have previously tried to introduce British HO scale, but had not been successful. Some more experienced modellers, dissatisfied with the scale/gauge discrepancy of OO have replaced the 16.5mm gauge track and wheels with 18mm gauge track and wheels. This is known as EM gauge. EM stands for Eighteen Millimetres. This is a specialist scale not commonly seen in Australia.
Taking this gauge accuracy to further extremes, there are some modellers who choose to reduce all dimensions exactly to 1:76 scale, particularly wheel flanges and flangeways at turnouts. This is known as P4 (ProtoFour). Track gauge is around 18.83

Most manufacturers of OO scale will fudge a little on the gauge so that the locomotives and rolling stock will run on HO track

• It’s easy to find accessories and features that are designed for the HO scale
• HO accessories tend to be very affordable

• May be a little too small for very young children to handle effectively
• Requires a little more space than the N scale, so it may not be suitable for people who have very limited amounts of space.

The models are nearly half the size of HO / OO and as a result you can get much more track and scenery into the same space as those scales.

N is generally 1:160th scale, or 2mm to the foot. The track gauge is 9mm. N stands for Nine

• Offers a nice compromise that allows people to create very realistic and detailed layouts with limited amounts of space
• Gradual curves are possible, which makes this scale much more versatile
• Although there aren’t quite as many N accessories as O accessories, new options are made available all the time. As N scale becomes more popular, more options should become available.

• The smaller size of N scale trains and accessories make it a less-than-optimal choice for young children and elderly enthusiasts who may have trouble working with small pieces of rolling stock
• Fewer accessories are available, so achieving the perfect layout is more difficult
• Prices tend to be a little higher for N-scale trains and accessories

Most OOO gauge was from Lone Star Locos which was a range of die-cast push-along trains made in the UK

They ran on metal track closer to 8.5mm gauge. Later some electrically powered models were made, but they are relatively rare today

The well known Hornby tinplate trains of the pre 1960’s were O gauge (32mm). In the past (about 100 years ago), the model train sizes were referred to by numbers. Gauge 3, gauge 2 and gauge 1 (45mm) being the smallest. So when a smaller size was introduced, the “baby” trains were known as 0 gauge.

Today 0 or O gauge is considered large and few really have the room for it inside. Models are to 1:43 (UK) to 1:48 (US).

The locomotives are big and impressive and are a favourite of young and old “kids” alike. The 2-rail version runs on DC current. The O scale trains tend to dwarf the scenery unless you have a very large room for the layout, but they sure are fun to run!

O27 Scale: This is also 1:48 scale, but the difference is in the tighter curves. (O27 track sections will make a 27″ circle compared to the standard O scale track sections which will form a 31″ circle.) Also, O27 rail is a little shorter and thinner than standard O scale. Lionel is the primary, or at least the most famous, manufacturer of O27 these days – most, if not all, produced in the 3-rail version running on AC current. Lots of accessories are available with working parts (circuses, sawmills, etc).

Another Gauge is On30 means the models are O scale (1:48 running on 32mm gauge track). But the ‘n’ signifies Narrow gauge. 30 means 30 inches, or 2.5 feet. This means the full size train runs on 2 foot, 6 inch gauge track (Puffing Billy in Victoria, Australia is one example of a 2.5 foot gauge railway). So the model must also run on narrower track. It just so happens that 16.5mm gauge (HO) track is an almost exact match for 30 inches in 1:48 scale, so what we have is O scale trains running on HO track. This size is gaining popularity due to Bachmann’s ready to run models in On30 scale. It allows a layout that takes no more room than HO scale, but the extra size to construct more detailed models.

• The large size of this scale makes it suitable for young kids and elderly people, who have a much easier time manipulating larger pieces
• This is a fairly popular scale, so there are plenty of accessories on the market
• Rolling stock and engines can be enhanced so that they look very realistic because of the large size of this scale
• On30 has many of the advantages of G scale without the serious cash outlay. You also don’t need so much space

• A lot of space is needed in order to make an O-scale layout look realistic at all
• The larger size of this scale means that it tends to be more expensive. It’s often necessary to spend a lot more money to complete a single layout
• Much sharper turns are needed due to space constraints, which makes these sets look a lot less realistic and more like toys

Good size for running a train around a Christmas tree!

Commonly used for garden layouts. Also called LGB scale. If you like working outdoors, doing real landscaping and gardening, this is the most likely model train scale you’ll want to use.

G gauge was introduced in 1968 by Lehmann of Germany.

The gauge is 45mm. LGB, by the way, is a brand name. It stands for Lehmann Gross Bahn (Lehmann being the manufacturer, gross bahn being German for large railway) The models are weatherproof and look great set up in the garden.

• Most of the pieces made in G scale are also designed to be used outdoors, which makes it easy to create a garden railroad
• This scale’s exceptionally large size makes it suitable for very young children and for older adults who have difficulty manipulating small pieces
• Great for outdoor use or large rooms.
• Very easy to handle and generally very well constructed.
• If you like trains that run when they are supposed to and easy to set up, then consider G gauge

• High-quality rolling stock, engines, track, and accessories are very expensive
• This scale isn’t nearly as standardized as other scales, as evidence by the size disparities between manufacturers
• Pickings are slim in terms of accessories
• A massive amount of space is needed to create a G-scale layout.
• Not ideal if you are short on space, however, the smallest radius track is 600mm, so it can be fitted into a relatively small area considering its large scale.
• Models seem expensive at first, but do actually represent value for money if you investigate further.

• 1not as popular as some of the others but definitely has a rowing as a home for a lot of followers and offspring from the American Flyer era

With a scale of 1:100 (in some countries this is 1:120) and 12 mm gauge, this Scale is only supported by a relatively small number of manufacturers.

TT Scale was superseded by N Scale in the 1960’s before it had much of a chance to establish itself.

TT stands for “Table-Top” as it was an ideal size to set up on an average sized table.

Modellers use TT track and mechanisms with their HOn3½ Scale, which represents 3’6″ gauge in HO scale.

• May be a option if space is a major issue

T stands for Three (3) mm gauge.

A relatively new scale for model railways (introduced in 2007 by Japanese company, K K Eishindo), it is a 2-rail electric system running on 4.5 – 5 volts with motorised trains.

• There is a range of scenery, structures, track and all you need to construct a working model railway in a very small space

Made by Tiny Trains of South Dakota, these pre-built layouts use cast metal trains attached to a belt under the ‘track’.

TY stands for “TinY”

• May be a option if space is a major issue

• Train consists cannot be altered
• Turnouts are not available

Z

Introduced by Marklin of Germany in 1972, it is 1:220 scale and runs on 6.5mm gauge track.

Marklin is one of only a few manufacturers to support Z Scale, although there seems to be random products available from a handful of US and Europeancompanies.

•  Easier to transport as it may require less space
• an entire Z scale model railroad empire can fit inside a suitcase
• can be used effectively in the background of an N scale or HO scale layout for forced perspective so that it looks like you have trains or structures way off in the distance when viewed from eye level. This makes your HO or N scale layout look even bigger than it really is.
• This scale is great for coffee tables, a nice addition to your executive desk
• Also a good choice for any “large” layout in a very small space.

•  Small size me a challenge for people who cannot see properly
• Smaller size means less detail
• Limited availability
• Limited production and manufacturing means less choices and typically higher prices
• Relatively expensive compared with N scale (probably the main reason it has never become as popular as N), and with a much more limited range of models available. -It does not use a great deal less space than N scale.

The prototypes for narrow gauge railways are usually logging railroads where sharp turns around rocky, mountainous terrain are required.