A lot of people understandably get confused when it comes to model railways, especially when it comes to gauges and scales. One of the most common questions we hear is:
What scale is OO Gauge?
The scale of OO Gauge model railways is 1:76 scale.
But what do “gauge” and “scale” actually mean? Let’s break it down as simply as possible.
What Is OO Gauge?
OO Gauge refers to the distance between the rails on the track, which is 16.5mm. Interestingly, this is the same as HO Gauge, which is popular internationally. However, in OO Gauge, the trains themselves are built to a 1:76 scale, not 1:87 like HO. This means the trains are slightly larger in proportion to the track than you’d expect.
This quirk dates back to when early electric motors wouldn’t fit inside smaller HO scale British locomotives. OO was born as a workaround—and it has stuck!
What Does 1:76 Scale Mean?
1:76 Scale means that every part of the model is 76 times smaller than the real-life version. So, if a real-world truck was 16.5 metres long, the model version would be approximately 217mm (or about 21.7cm) long.
You’ll often see “OO Gauge” and “1:76 scale” used interchangeably, especially for accessories, vehicles, and buildings. While the terms aren’t strictly the same, they’re usually compatible when building a layout.
OO Gauge vs. Other Popular Scales
So, should you build an OO Gauge layout? Or would another scale be better for your needs?
Let’s look at the most common options in the UK:
OO Gauge (1:76 Scale)
- Most popular in the UK
- Huge range of trains, buildings, vehicles, and scenery
- Big enough to detail, small enough to fit a lot in a limited space
N Gauge (1:148 Scale)
- Much smaller than OO Gauge
- Great for layouts in tight spaces
- Still has a good range, but less extensive than OO
O Gauge (1:43 Scale)
- Significantly larger
- Highly detailed, but requires more space (and budget!)
- Less common for beginners
TT:120 (1:120 Scale)
- TT stands for “Table Top”
- Recently reintroduced by Hornby, led by Simon Kohler
- A growing category, with more manufacturers joining in
- Great middle ground between N and OO in terms of size
So... Should I Choose OO Gauge?
I personally love OO Gauge. It offers the perfect balance between size, availability, and visual detail—especially if you’re just starting out. But really, it all comes down to your space, budget, and what you want to build.
Frequently Asked Questions
Is OO Gauge the same as HO Gauge?
No. OO Gauge uses the same track gauge (16.5mm) as HO, but the models are built to 1:76 scale, not 1:87. So, OO trains are larger in scale but run on the same track width.
Can I use 1:76 scale cars and figures on my OO Gauge layout?
Yes! Since OO is 1:76 scale, any vehicles, buildings, or accessories marked 1:76 will work perfectly.
What’s the best gauge for beginners?
For UK beginners, OO Gauge is usually the best choice. It offers the widest range of products, is easy to work with, and is well-supported by guides, clubs, and communities.
Final Thoughts
Whether you're brand new to model railways or just exploring different scales, understanding the difference between gauge and scale can help build a layout you’ll truly love.
If you're ready to get started, check out our OO Gauge products and browse our full range of 1:76 scale diecast model vehicles!