Gravel & Subbase Calculator
Interactive Gravel Calculator
ENGINEERING SCHEMATIC
Compacted Aggregate Crushed Stone Subbase Total Aggregate Weight Required
3.98 US tons
(7,951 lbs / 3.61 tonnes) Compacted Volume to Order
2.84 cu yds
76.7 cu ft (2.17 m³) Raw Trench Volume
2.47 cu yds
Before 15% compaction settlement Material Density
1.40 tons/yd³
Standard quarry deliverable state Why Subbase Gravel is Critical Under Concrete
Pouring concrete directly onto uncompacted expansive clay or native topsoil leads to uneven subgrade settlement, moisture trapping, and severe frost heave cracking. A compacted 4-to-6 inch layer of washed crushed stone (#57 stone or crusher run) provides three fundamental engineering benefits:
- Uniform Load Distribution: Distributes wheel and structural loads evenly across the underlying subgrade.
- Capillary Moisture Break: Coarse stone prevents groundwater capillary action from wicking up through the bottom of the concrete slab.
- Free-Draining Frost Protection: Prevents pooling water under the slab from expanding during freeze-thaw cycles.
Aggregate Density Reference Table
| Material Type | Tons per Cubic Yard | Pounds per Cubic Foot | Primary Construction Purpose |
|---|---|---|---|
| #57 Crushed Stone | 1.40 | 104 lb/ft³ | Slab base, drainage trenches, french drains |
| Crusher Run / DGA | 1.50 | 111 lb/ft³ | High-compaction driveways, parking pads |
| Pea Gravel | 1.45 | 107 lb/ft³ | Pipe bedding, decorative walkways, exposed aggregate |
| Concrete Sand | 1.35 | 100 lb/ft³ | Bedding layer, concrete mixing |