Calculators / Decomposed granite
Paths and xeriscape
Decomposed granite calculator
Paths, patios and low-water landscapes. DG compacts to a firm surface, so depth is measured after compaction — order for the loose volume.
How deep, by project
| Project | Depth | Notes |
|---|---|---|
| Garden path, foot traffic | 2 in compacted | Over a firm subgrade with edging. Two inches is plenty underfoot. |
| Patio or seating area | 3 in compacted | Laid in two lifts, watered and plate-compacted between them. |
| Driveway or parking pad | 4 in compacted | Over a 4-inch crushed base. Straight DG on soil will rut. |
| Stabilised DG | 3 in compacted | Mixed with a binder before compaction. Costs more, sheds water instead of eroding. |
| Around stepping stones | 2 in | Level with the stone top so the edges do not become trip points. |
Order loose, finish compacted
Decomposed granite is granite that has weathered into a mix of coarse grit and fines. Those fines are what let it compact into a hard, walkable surface — and they are why the pile you buy is bigger than the path you end up with.
Expect to lose around a fifth of the loose volume during compaction. If you want 3 inches of finished path, you are spreading close to 4 inches loose. The calculator's extra allowance covers most of this; bump it to 15 percent for larger jobs.
Water it, then compact it
Dry DG will not bind. The sequence is spread, mist until damp but not saturated, then plate-compact, in lifts of no more than 2 inches at a time. Compacting a single 4-inch layer leaves the bottom half loose.
This is also the difference between a path that sheds rain and one that channels it into ruts.
Erosion is the honest downside
Unstabilised DG on any slope will move in heavy rain, and it tracks indoors on shoes. Stabilised DG, mixed with a binder before compaction, costs noticeably more per ton but holds up.
Solid edging on both sides of a path is the cheapest improvement you can make to either version.
Common questions
How much decomposed granite do I need?
Area times depth, plus about 20 percent for compaction loss. One cubic yard covers roughly 108 square feet at 3 inches loose.
How deep should decomposed granite be?
Two inches compacted for footpaths, three for patios, four over a crushed base for anything a vehicle drives on.
How much does a yard of decomposed granite weigh?
About 2,700 pounds, or 1.35 tons — similar to crushed stone, because that is essentially what it is.
Does decomposed granite need edging?
For any defined path or patio, yes. Without an edge the fines wash out at the margins and the surface unravels from the sides inward.
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