A model railroad scale converter translates real-world prototype dimensions into the smaller measurements used for model trains. Understanding scale is essential when kitbashing structures, scratch-building scenery, or mixing accessories from different manufacturers. Enter a real dimension or convert between any two scales instantly.
Enter Dimension
e.g. 6.667 ft = standard door height (6'8")
Quick examples
Result
Enter a dimension and click Convert
Scale Comparison Table
Enter a dimension above to see all scale equivalents
| Scale | Ratio | Model Size | Common Use |
|---|---|---|---|
| No data yet — enter a dimension above | |||
How to Use the Model Railroad Scale Converter
Model railroad scales define the ratio between a prototype (real-world) object and its miniature counterpart. The most common scale worldwide is HO (1:87), meaning every dimension is divided by 87 to get the model size. This converter makes scale math instant — no need to divide by hand or keep a reference sheet nearby.
Step 1: Choose Your Unit System
Toggle between Imperial (feet/inches) and Metric (meters/millimeters) using the toggle at the top right. Imperial is the default since most North American prototype dimensions use feet and inches. European modelers will prefer metric.
Step 2: Enter the Real-World Dimension
Type the prototype measurement you want to convert. Common reference points: a standard door is 6'8" (6.667 ft), a boxcar is 40-50 feet long, a typical single-story building is 10-12 feet tall. For scale-to-scale conversions, enter the measurement you have and set "From scale" to that scale.
Step 3: Select From and To Scales
If converting from the real world, leave "From scale" as "Real world (prototype)." If you have an HO model and want to know the equivalent N scale size, set "From" to HO. Then choose your target scale in the "To scale" dropdown.
Step 4: Read the Scale Comparison Table
The comparison table below the converter shows the same prototype dimension converted to all 7 scales simultaneously. This is useful when deciding which scale fits your layout space — for example, a 50-foot boxcar measures 172mm in HO but only 98mm in N scale, making N almost twice as space-efficient.
Common Scale Reference Points
Z (1:220) — smallest common scale, fits in a briefcase. N (1:160) — popular compact scale. TT (1:120) — gaining popularity, between N and HO. HO (1:87) — most popular worldwide, excellent detail availability. S (1:64) — American Flyer standard. O (1:48) — Lionel standard, very detailed. G (1:22.5) — garden railways, outdoors.
FAQ
Is this model railroad scale converter free?
Yes, completely free with no signup required. All calculations run locally in your browser.
What model railroad scales does this tool support?
This converter supports all major scales: Z (1:220), N (1:160), TT (1:120), HO (1:87), S (1:64), O (1:48), and G (1:22.5). HO is the most popular scale worldwide, while N is the most popular compact scale.
How do I convert a real-world dimension to HO scale?
Simply enter the real-world measurement in feet or meters, select HO as the target scale, and the converter shows the model dimension instantly. For example, a 6-foot 8-inch door converts to about 23mm in HO scale (1:87).
What is the most popular model railroad scale?
HO scale (1:87) is the most popular worldwide because it offers a good balance between detail and space requirements. N scale (1:160) is popular for smaller layouts, while O scale (1:48) is favored for its large, highly detailed models.
Can I compare dimensions across all scales at once?
Yes. Enter any real-world dimension and the tool shows the equivalent measurement in all 7 scales simultaneously, making it easy to compare how the same prototype looks in different scales.
How do I convert between two different scales?
Set the 'From' dropdown to the scale you have and the 'To' dropdown to the scale you want. The converter handles scale-to-scale conversions, useful when you want to use a structure or accessory from a different scale or adapt an N scale model for HO.