Hobbies
Model train scale converter
Every model railroad question starts with the same arithmetic: a 40-foot boxcar is 5.5 inches long in HO, and everything else follows from the ratio. This train scale converter handles Z (1:220), N (1:160), TT (1:120), HO (1:87.1), OO (1:76), S (1:64), O (1:48), and G (1:22.5) in both directions — type a real dimension in feet, inches, centimeters, or meters and get the model size in inches and millimeters, or measure a model and recover the real-world size. The comparison line sizes the same object in Z, N, O, and G at once, so deciding whether a helper yard fits on the shelf takes one glance instead of six divisions.
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Scale ruleDimensions converted — a scale rule reads them straight off the layout.Check current price ↗As an Amazon Associate, CalcForged earns from qualifying purchases.The math, plainly
How it works
- 01
Each scale is a ratio — HO runs 1:87.1 (3.5 mm to the foot), N 1:160, O 1:48, OO 1:76, G 1:22.5.
- 02
Real → model divides your dimension by the ratio after converting to inches; model → real multiplies back out.
- 03
The comparison line sizes the same real object in Z, N, O, and G so you can see at a glance which scale fits the shelf you actually have.
Try a real scenario
40 ft boxcar in HO
Inputs40 ft, HO (1:87.1)
ResultAbout 5.5 in long (140 mm) — the same boxcar is 3.0 in in N and 10.0 in in O.
Gear for the job
Tools & materials people actually buy
Scale rule
A dedicated scale rule reads dimensions directly in HO, N, and O — no math mid-project.
Starter track pack
Nickel-silver track in the gauge your scale runs — match rail size to era.
Knuckle couplers
Mates rolling stock across brands — the hobby default for a reason.
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