Decomposed granite calculator
Decomposed granite shrinks when you compact it, so you need to order more loose material than the finished depth suggests. This calculator does that conversion for you.
Estimates round up. Check product labels and supplier figures before ordering.
How deep should decomposed granite be?
| Project | Finished depth | Base underneath |
|---|---|---|
| Garden path | 2-3 in | Optional, 2-4 in on soft soil |
| Patio or seating area | 3-4 in | 2-4 in crushed base |
| Busy walkway | 3-4 in | 4 in crushed base |
| Driveway | 4-6 in | 4-6 in crushed base |
How it's calculated
Decomposed granite (DG) is sold loose, but you measure the job by its compacted depth. The calculator works back from the finished depth to the loose volume to order.
Compacted cu ft = area (sq ft) x finished depth (in) / 12
Loose cu ft = compacted cu ft / (1 - compaction %)
Tons = loose cubic yards x 1.35
Example: a 200 sq ft path with 5% extra is 210 sq ft. At 3 inches finished depth that is 52.5 cubic feet compacted. With 20% compaction you need 52.5 / 0.8 = 65.6 cubic feet loose, or 2.43 cubic yards, about 3.3 tons. In bags that is 132 half-cubic-foot bags.
DG compacts more or less depending on how fine it is, how damp it is, and how hard you tamp it. Plan on 20 to 25% with a plate compactor. Lay it in 1 to 2 inch lifts, mist each lift, and compact before adding the next. Stabilized DG compacts in a similar way but is harder once cured.
What you'll need
- Decomposed granite
- Plate compactor rental
- Steel landscape edging
- Dg stabilizer
- Landscape fabric
Common questions
How much does a yard of decomposed granite weigh?
About 1.35 tons, or 2,700 pounds, loose. Damp DG weighs more.
How much does decomposed granite compact?
Roughly 20 to 25% by volume with a plate compactor, so 3 inches of loose DG ends up around 2.25 to 2.4 inches.
How deep should a decomposed granite path be?
About 2 to 3 inches compacted for a garden path and 3 to 4 inches for patios or busy walkways, ideally over a compacted crushed base.
Do I need edging for decomposed granite?
Yes. Steel, aluminum or paver edging keeps DG from migrating into lawns and beds and helps it hold its compacted shape.