F is the scale designator for 15mm to the foot scale. That works out to 1/20.3 in a ratio. That's it. Simple.
Then we get into the modifiers that confuse some....F being the basic scale....
Fn3 means 1/20.3 scale on a prototypical 3' wide track...resulting in a 45 mm track gauge (3 ft at 15mm /ft = 45mm) for modeling. Of note....45mm track is also called Gauge 1 track.
Fn2 means 1/20.3 on prototypical 2' wide track....resulting in a 30 mm track gauge (2 ft at 15mm/ft = 30 mm) for modeling.
F, without the narrow gauge delimiter
, is standard gauge (4' 8.5") That would make the track gauge 70.5 mm wide for modeling (4' 8.5" = 4.7083' ... 4.7083' ft at 15 mm/ft = 70.5 mm).
In all cases...the buildings, people, cars, trucks, trees, etc are the same scale...F...or 1/20.3...15mm to the foot.
This is the same nomenclature system used in HO and O gauge. HOn3 means 1/87th scale models operating on 3' gauge track. On3 means 1/48th scale models working on 3' gauge track. Now....there's one variation....On30 means 1/48th scale models operating on 30" gauge track.
