How much ballast do I need for OO gauge?

For OO gauge, the ballast bed is typically 30mm wide and 3mm deep. A metre of single track needs roughly 60-70g of ballast. A typical starter layout of 3-4 metres of track needs about 200-300g. Points need extra as they are wider.

What size ballast should I use?

For N gauge use fine ballast (under 1mm grain). For OO/HO use medium ballast (1-2mm grain). For O gauge use coarse ballast (2-3mm). Real ballast is 30-50mm, so divide by your scale ratio for the correct model grain size.

How do I fix ballast in place?

Spread dry ballast along the track, brush it into shape with a soft brush, then apply diluted PVA glue (50:50 with water plus a drop of washing-up liquid) using a dropper or pipette. Let it dry for 24 hours before running trains.

ModelCalcs

Ballast Calculator — Model Railway

Calculate ballast volume and weight needed for model railway track sections.

Track Length

Total length of track to ballast

GaugeTrack gauge and scale

Track TypeSingle or double track mainline

Points / Turnouts

Number of points that need ballasting

Ballast Bag Cost

Cost per bag of ballast

How We Calculate This

Calculation

Cross-section area = Ballast width x Depth x 0.7 (trapezoidal profile)

Volume = Total track length x Cross-section area

Weight = Volume x Ballast density (1.5 g/cm3)

Points are treated as extra track length based on gauge. The trapezoidal factor (0.7) accounts for the sloped shoulder profile of realistic ballast.

Frequently Asked Questions

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Last updated: March 2026

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