Both OO and HO gauge trains are two of the most popular model railway scales - but are you able to run OO model trains on HO track?

Before we answer this question, let's evaluate these two popular model railway sizes and consider the differences between scale and gauge in model trains.

HO gauge is a popular size in Continental Europe and North America. Model trains and track in this gauge have a scale ratio of 1:87 or 3.5mm to 1 foot.

OO gauge is the most popular model railway gauge in the UK and was originally made famous by Hornby. The track in this gauge is the same scale as HO - a scale ratio of 1:87 or 3.5mm to 1 foot. However, the locomotives and other models (e.g. buildings) in an OO gauge layout have a scale ratio of 1:76 or 4mm to 1 foot.

You may be wondering why the scale for OO gauge locomotives and buildings is different to OO gauge track, and this is certainly a very valid query.

Put simply, when OO gauge was first created the most popular model trains were produced in HO gauge. In order to maintain backward compatibility with these existing products, and to keep production costs as low as possible, OO gauge was designed to use HO size track. However, due to UK locomotives being smaller than their European counterparts, there was insufficient space inside the models to accomodate the motors at this scale. As a result, the bodies of OO gauge model trains were produced to the slightly larger 1:76 or 4mm to 1 foot, and it has remained that way ever since they were first introduced.

Are OO Trains Compatible with HO Track?

Yes, they are. As we've explored above, the track for both OO and HO gauge model trains has a width of 16.5mm, meaning OO trains can run on HO track.

Are OO or HO model trains better?

There's really no definitive answer to this question. It will ultimately come down to where you are located and your personal preferences with regard to your model trains. For example, in the UK and Ireland OO gauge trains are significantly more popular than HO, whereas HO model trains are generally preferred in North America and Continental Europe. There are a number of good quality train sets available in both these gauges and OO trains are compatible with HO track.

For information on the best OO and HO train sets be sure to refer to our complete guide to the best train sets for detailed product comparisons, expert reviews and specialist advice. It's essential reading if you're searching for the best train set and are looking for details on which type would be best for you.

Next Steps

For further reading on some essential model train knowledge be sure to check out our guide to the differences between DCC and DC train sets where we discuss the benefits of each and which technology is most suitable in an electric train set.

If you're on the lookout for a new train set in either OO or HO gauge, you should refer to our other guides in our train set series for a complete overview of the options available for different age groups and use cases. You'll find expert guides, recommendations and tips for choosing the best train sets for you.

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