Model Scale Calculator

A scale converter for people who build models.

Pick a scale — HO, N, O, 1:35 armour, 28mm heroic, 1/4" = 1' — type a dimension, and read the answer as you type. Free, offline, no account, no ads.

THREE ANSWERS, ONE SCREEN

• Real → model — how big is a 40-foot boxcar in HO?
• Model → real — this part measures 92 mm; what is that full size?
• What scale is this? — give a real length and the model length it has to come out at, and get the ratio.

COMPARE ACROSS SCALES

A second view takes one measurement and shows it in every scale in a hobby group at once — model railway gauges, military armour, aircraft, tabletop miniatures — with a proportional bar per row so you can judge the sizes by eye instead of reading numbers.

UNITS HOBBYISTS ACTUALLY TYPE

It parses what you would write on a workbench note: 250mm, 2.5 cm, 5' 6", 5ft 6in, 1 1/2", 3/4", 1-1/2". Feet-and-inches and fractional inches are first-class output formats, not an afterthought — fractions come back as fractions, rounded to the precision you choose.

SCALES INCLUDED

• Model railways — Z, N, TT, HO, OO, S, O, G and more
• Military and armour — 1:16, 1:35, 1:48, 1:72
• Aircraft — 1:32, 1:48, 1:72, 1:144
• Cars — 1:18, 1:24, 1:43, 1:64
• Tabletop and wargaming — 15mm, 28mm heroic, 32mm, 54mm
• Architecture — imperial drawing scales like 1/4" = 1' and metric 1:50, 1:100
• Any custom ratio you type

WORKS COMPLETELY OFFLINE

No account, no sign-in, no sync, no paywall and no advertising. Every calculation happens on your device, and nothing you type is ever sent anywhere. The only thing the app ever sends is anonymous usage data — which scales and modes get used — and you can switch that off in Settings.

For model railroaders, scale modellers, miniature painters, RC builders, dollhouse makers, architects and anyone who has ever stood in a hobby shop doing long division on their phone.