A garden railroad or garden railway is a model railway system set up outdoors in a garden. While G is the most popular scale for garden railroads, 16 mm scale has a dedicated and growing following especially in the UK. Model locomotives in this scale are often live steam scale models of British narrow gauge prototypes. 16 mm scale (which runs on 32 mm track), the same gauge as O gauge is probably now more popular in the UK than G scale.

A garden railway's scale tends to be in the range of 1/32 (Gauge 1) to 1/19 (1:19), running on either 45 mm (1.77 in) or 32 mm (1.26 in) 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". They are smaller than the Backyard railroad 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. Excellent footage of Garden Railway's some great engineering start collecting Daves Railway Films