HO or H0 is a rail transport modelling scale using a 1:87 scale. It is the most popular scale of model railway in the world. The rails are spaced 16.5 millimetres (0.650 in) apart for modelling 1,435 mm standard gauge tracks and trains in HO.
HO scale (1:87) model of a center cab switcher made by Bachmann, shown with a pencil for size comparison.
HO scale model of a CSX locomotive
First model railroad layouts in today's H0 gauge, 1926
HO scale steam locomotives at the N&W RR museum in Crewe, Virginia.
Railway modelling or model railroading is a hobby in which rail transport systems are modelled at a reduced scale.
One of the smallest (Z scale, 1:220) placed on the buffer bar of one of the larger (live steam, 1:8) model locomotives
HO scale (1:87) model of a North American center cab switcher shown with a pencil for size
Z scale (1:220) scene of a 2-6-0 steam locomotive being turned. A scratch-built Russell snow plow is parked on a stub (Val Ease Central Railroad).
A simple H0 (1:87) scale model railroad, consisting of three interconnected modules, each 70 x 100 cm in size. It has two concentric ovals of track and a few switches to sidetracks. It makes no pretension of being a copy of "real life". Using low-cost landscaping parts, house kits and rolling stock, it was built for a total of only a few hundred dollars.
