What is the maximum gradient for a model railway?

The recommended maximum is 3% (1 in 33). Up to 4% is possible with good traction, but trains must be short. Real UK railways rarely exceed 2% (1 in 50). The Lickey Incline, the steepest mainline gradient in England, is 1 in 37.7 (2.65%).

How do I calculate gradient as a percentage?

Gradient percentage = (Rise / Run) x 100. A 30mm rise over 1000mm run = 3%. The "run" is the horizontal distance, not the length along the slope (though for model railways the difference is negligible).

How do I build a smooth gradient?

Use risers every 200-300mm to support the track bed. Commercial incline kits (like Woodland Scenics) provide graduated risers. Start and end gradients gradually — sudden changes cause uncoupling. Use a spirit level and ruler to check consistency.

Will my trains run on steep gradients?

Most modern OO locos handle 3% with 3-4 coaches. Shorter wheelbase locos and those with traction tyres cope better with gradients. Heavy trains struggle above 2.5%. Test your specific locos on a temporary ramp before committing to your layout design.

ModelCalcs

Gradient Calculator — Inclines & Hills

Calculate gradient percentages and rise-over-run for inclines and hills on your model railway.

Rise (mm)

Vertical height gained

Run Length (mm)

Horizontal distance

Gauge

How We Calculate This

Calculates gradient from rise and run measurements, expressing it as percentage, ratio and angle.

Formula

Gradient % = (Rise / Run) x 100
Ratio = 1 in (Run / Rise)
Angle = arctan(Rise / Run) in degrees

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify quantities before purchasing materials.