Rocks by size and scale
Choose the Right Rock Size
The same real stone can look small, medium, or large depending on the modeling scale. Use the product-number ending as the starting guide.
Rock Size and Scale Guide
Start with the small-rock number for your scale, then move up one ending for medium and two or more endings for large rock.
| Rock size | N scale | HO scale | O scale | G scale |
|---|---|---|---|---|
| Small rock | ends in 3 | ends in 4 | ends in 5 | ends in 6 |
| Medium rock | ends in 4 | ends in 5 | ends in 6 | ends in 7 |
| Large rock | ends in 5+ | ends in 6+ | ends in 7+ | ends in 8+ |
Important: products with the special 03 suffix are grouped under Sand & Gravel and can also be used as rip rap. That 03 rule is separate from the general rock-size progression above.
Shop by Rock Size
Each page explains the matching product-number endings before the shopping links.
Need boulders or erosion stone?
Boulders and Rip Rap have their own rules and pages because they overlap several rock grades.
Boulder Guide → Rip-Rap Guide →