A garden railway or garden railroad is a model railway system set up outdoors in a garden. G Scale is the most popular scale for garden railroads, though 16 mm scale also has a following, especially in the United Kingdom. Model locomotives in this scale are often live steam scale models of British narrow gauge prototypes. 16 mm scale (which runs on) track, the same gauge as O gauge is probably now more popular in the UK than G scale.
A garden railway's scale is usually in the range of 1/32 (Gauge 1) to 1/12 (1:12), running on either or gauge track. 1/32 scale (1:32) is also called "three-eighths scale" meaning 3/8 of an inch on the model represents one foot on the real thing. For similar reasons, 1/24 scale (1:24) is also called "half-inch scale". Other popular scales are 1:29, 1:20.3 (representing gauge prototypes on track, 16 mm (1:19). They are smaller than the Backyard railroad, or what is commonly called a miniature railway, and would not provide a ride-on facility, being intended instead as a display railway. Smaller scales and gauges are used in the garden, but in general garden railway is used to refer to the medium scale sizes which would be impractical to use indoors.