Free tools for model railroad enthusiasts. Convert scales, calculate speeds, plan grades, design helixes, and estimate power requirements for HO, N, O, G, Z and all popular scales.
Convert between real-world measurements and model scale dimensions.
Common conversions: A 50-foot boxcar in HO scale is about 6.9 inches. A 6-foot person in N scale is about 0.45 inches tall.
Calculate scale speed equivalents for realistic train operation.
For realistic operation, freight trains typically run 30-50 mph, passenger trains 60-79 mph, and high-speed trains over 100 mph. Run your models slower than you think—they'll look more realistic!
Calculate track grades and inclines for your layout.
0-2%: Ideal for long trains, minimal locomotive strain. 2-3%: Good for most layouts, manageable train lengths. 3-4%: Moderate, may need helper locomotives for long trains. 4%+: Steep, limit to short trains or use multiple locomotives.
Find recommended curve radii and convert between radius measurements.
Arc Length
Select a scale to see minimum radius recommendations.
| Scale | Minimum (inches) | Minimum (mm) | Recommended for Long Cars |
|---|
Calculate how much track you need for straight runs, curves, and more.
Design a helix to change elevations between layout levels.
Ensure adequate vertical clearance between turns (typically 3-4 inches for HO). Account for track thickness, roadbed, and tallest rolling stock. Consider access for derailments!
Estimate locomotive pulling capacity and train limits based on grade.
Maximum cars on this grade
For reliable operation, the NMRA recommends: HO Scale: 1 oz + 0.5 oz per inch of car length. N Scale: 0.5 oz + 0.15 oz per inch. Heavier cars track better but reduce train length on grades.
Complete reference data for all popular model train scales.
| Scale | Ratio | Gauge (mm) | Gauge (in) | Min Radius | Standard | Description |
|---|
| Real Size | Z (1:220) | N (1:160) | HO (1:87) | O (1:48) | G (1:22.5) |
|---|
| Prototype Speed | Z (in/s) | N (in/s) | HO (in/s) | O (in/s) | G (in/s) |
|---|