Bags of Decomposed Granite for a 20x30 Patio
How many bags of decomposed granite for a 20x30 patio: at 3 inches deep you need about 150.0 cubic feet, which is 300 bags of the common 0.5 cubic foot size. If your store sells decomposed granite in 50-pound bags instead, figure about 300 bags, since decomposed granite weighs roughly 100 pounds per cubic foot.
Volume and tonnage calculator →Bag count by depth
| Depth | Cubic feet | 0.5 cu ft bags | 50 lb bags (approx.) |
|---|---|---|---|
| 1 in | 50.0 | 100 | 100 |
| 2 in | 100.0 | 200 | 200 |
| 3 in | 150.0 | 300 | 300 |
| 4 in | 200.0 | 400 | 400 |
How to figure it
- Area: 20 × 30 = 600 sq ft.
- Volume: 600 × (3 ÷ 12) = 150.0 cu ft.
- Bags: 150.0 ÷ 0.5 = 300 bags (round up).
Bags or bulk?
A cubic yard is 27 cubic feet, so 150.0 cubic feet is 5.56 yards, about 7.5 tons. Past about a yard, bulk is usually less work and often less money. Compare the bag price × 300 against a bulk quote for 8.2 tons delivered.
About decomposed granite
Decomposed granite (DG) is weathered granite broken into small particles and fines. It packs into a firm, natural-looking path surface, and stabilized versions include a binder.
Install tips for a patio
- Dig and level. Remove sod and set the base slightly below the surrounding grade.
- Edge it. Steel, plastic or stone edging keeps material in place.
- Spread in layers. Rake to depth, then tamp or wet and compact.
- Buy a few extra. Grab 5 to 10 percent more bags for settling and touch-ups.
The volume and tonnage calculator handles other sizes and depths.
Good and poor uses for decomposed granite
Works well for:
- Garden paths and patios with a natural look
- Around trees and in xeriscape designs
- Stabilized DG for accessible paths
Less suited to:
- Steep grades without a stabilizer
- Areas right outside doors, since fines track in
- Driveways with heavy turning traffic
Quick reference numbers
- Per inch over 100 sq ft: about 0.42 tons of decomposed granite (0.31 cubic yards).
- Per inch over 1,000 sq ft: about 4.2 tons.
- Another size for comparison: a 20x25 area at 4 inches takes about 8.3 tons.
- Weight used here: about 1.35 tons per cubic yard.
Common estimating mistakes
- Ignoring the base. A thin surface layer over soft soil fails early no matter how much material is on top.
- Skipping drainage. Water sitting under any surface softens the base and leads to ruts and potholes.
- Assuming every supplier uses the same weight. Two yards selling the same product name can quote different tons per yard.
- Using inches as if they were feet. Depth has to be divided by 12 before you multiply; skipping that step inflates the order twelvefold.
Questions people ask
How many bags of decomposed granite for a 20x30 patio?
About 300 bags of 0.5 cubic feet at 3 inches deep.
How many 50 lb bags of decomposed granite for 20x30?
About 300 bags at 3 inches.
How many 0.5 cubic foot bags are in a cubic yard?
54 bags.
How many cubic feet is a 20x30 patio at 3 inches?
About 150.0 cubic feet.
When does bulk make more sense?
Usually once the job passes about a cubic yard, or when you would need more than a few car trips.
Related guides
- Crushed Stone vs Gravel: Differences and Best Uses
- Tons to Cubic Yards for Gravel: Conversion Chart
- How Much Does a Ton of Gravel Cover? Depth Chart
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