Is my math correct?

[dudeface]

If an O gauge railway (1.25") is a model of an 18 inch gauge railway would I be correct in that it would be 21mm scale? This is what I'm thinking of doing for my eventual garden railway.

[drewzero1]

Technically yes (probably), but it's most commonly referred to as 7/8 inch scale (SE for short- as in, 7/8 inch to the foot). The track that we'd usually refer to as O gauge is usually called 32mm gauge on here. 32mm is very uncommon in US gardens but I've been building mine to that gauge as well... So far it's worked out cheaper but prevents me from visiting stock with a friend who runs G-scale/1-gauge/45mm track (which is almost universal in US garden railroads).

All that said, 7/8 is a great scale that seems to be popular for live steam, often some chunky or even whimsical models.

[ge_rik]

Yes, SE Scale. There are quite a few suppliers who produce SE scale models and figures

https://en.m.wikipedia.org/wiki/SE_scale

Rik

[dudeface]

Thanks, good to know it's a common scale. I prefer gauge 1 but I can live with o gauge as it's much easier to find parts and track for a reasonable price.