Find the gravel you need under each tube.
⚙️Calculation Parameters
📊Calculated Output
How Gravel Base Volume Calculator Works?
To size a gravel base, the Gravel Base Volume Calculator finds the cylinder of stone at the bottom of each hole, using the hole width and gravel depth. The process takes 4 steps.
Enter the hole diameter
Type the dug hole width, which is usually 4 in to 6 in (10 cm to 15 cm) wider than the tube.
Enter gravel depth
Type the compacted stone depth, commonly 4 in to 6 in.
Enter the hole count
Type the number of holes.
Read gravel quantities
The calculator shows cubic feet (ft³), cubic yards (yd³), tons and 0.5 ft³ bags of crushed stone.
Gravel Base Volume Calculator Formula
The Gravel Base Volume Calculator applies the cylinder formula to the hole bottom.
Gravel volume
V = n × π × (D_hole ÷ 24)² × (t ÷ 12)D_hole and t in inches.
Gravel weight
W ≈ V × 100 lb/ft³Crushed stone weighs about 95 to 110 lb/ft³ (1,520 to 1,760 kg/m³).
Tons
Tons = W ÷ 2,000US short tons.
Worked example: 10 holes, 20 in wide, 6 in of gravel
- V = 10 × 3.1416 × (20 ÷ 24)² × 0.5 = 10.91 ft³
- 10.91 ft³ = 0.404 yd³
- Weight ≈ 1,091 lb (0.55 tons), or 22 bags of 0.5 ft³ stone
Gravel Base Volume Calculator Conversion Table
The gravel base conversion table lists the stone needed per hole and for 10 holes at 6 hole sizes.
| Hole | Gravel depth | ft³ per hole | ft³ for 10 holes | yd³ for 10 holes | Tons for 10 holes |
|---|---|---|---|---|---|
| 16 in hole | 4 in | 0.465 | 4.65 | 0.172 | 0.23 |
| 18 in hole | 4 in | 0.589 | 5.89 | 0.218 | 0.29 |
| 20 in hole | 6 in | 1.091 | 10.91 | 0.404 | 0.55 |
| 24 in hole | 4 in | 1.047 | 10.47 | 0.388 | 0.52 |
| 24 in hole | 6 in | 1.571 | 15.71 | 0.582 | 0.79 |
| 30 in hole | 6 in | 2.454 | 24.54 | 0.909 | 1.23 |
Weight uses 100 lb/ft³. Use 3/4 in (19 mm) crushed stone for drainage.
What is Gravel Base Volume Calculator?
A Gravel Base Volume Calculator is a material calculator that estimates the crushed stone placed under each Sonotube to drain water and level the base.
Water that pools under a pier freezes and lifts it. A layer of compacted crushed stone gives water a path out and gives the tube a flat, firm seat. The stone fills the full hole width, not the tube width, so the calculator uses the hole diameter.
Ten 20 in holes with 6 in of stone need 10.9 ft³ of gravel, or about 0.55 tons.
What are the uses of Gravel Base Volume Calculator?
There are 4 main uses of the Gravel Base Volume Calculator.
Drainage beds
Builders place stone under every pier for drainage.
Bulk stone orders
Contractors order gravel by the ton or yard.
Bagged stone
Owners count 0.5 ft³ bags for small jobs.
Leveling
Crews set tube bottoms at an even elevation.
🔗Related Sonotube Calculators
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Tube and Square Footing Calculator
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