Tools for N- and Nm-scale calculations

Model railway calculators for N scale (1:160) and Nm scale (1:160). Convert prototype and model dimensions, calculate train speeds, gradients, and helixes for realistic layout planning and operation.

➡️Calculators for Z-scale (1:220)

Prototype to model length

1 : 160

Enter a dimension in either field. Results are shown in the most suitable unit.

Prototype dimension Scale model dimension

Type km, m, cm, or mm after the value. If omitted, metres are assumed. For example, 160 mm is 1 mm at N scale.

Prototype to model speed

1 : 160

Enter a speed in either field. Results are shown in the most suitable unit.

Prototype speed Scale model speed

Allowed units: km/h, m/s, cm/s, and mm/s. If omitted, m/s is assumed.

Track gradient

N scale

Enter the vertical height change and horizontal track length.

Height change Track length Gradient -- % Rise per metre -- mm/m

Enter units as mm, cm, or m. Unitless values are treated as metres. Gradient is height change divided by track length.

Helix calculator

N scale

Set the diameter and turns, then enter either the height gain or grade.

Diameter Number of turns Height gain Grade Total track length -- m

Use mm, cm, or m for diameter and height. Unitless values are metres. Editing height gain or grade updates the other value.

Compare model scales

Z · N · TT · H0

Enter a prototype length or area to compare its model size across scales.

Measurement Prototype value Unit

Z (1:220)--

N (1:160)--

TT (1:120)--

H0 (1:87)--

For area, the scale ratio is applied in both dimensions. Area units are displayed squared, such as cm².