Type 3 Stone Calculator: Volume & Weight

This calculator works out the volume and weight of Type 3 stone (a compactable crushed aggregate) needed for a project. You enter the length, width, and depth of the area to be filled, and the calculator returns the volume in cubic yards (or cubic meters) and the estimated weight in tons (or kilograms). The weight estimate uses a typical density range for compacted Type 3 stone, so you can plan deliveries and compare quotes with confidence.

Formula

The core formula is straightforward: Volume = Length × Width × Depth. All dimensions must be in the same unit. For weight, multiply the volume by the material’s density (weight per unit volume).

• V = volume (cubic feet, ft³)
• L = length (feet, ft)
• W = width (feet, ft)
• D = depth (feet, ft; convert inches to feet by dividing by 12)
• ρ = density (pounds per cubic foot, lb/ft³)
• Weight (tons) = V × ρ ÷ 2000 (since 1 US ton = 2000 lb)

Worked Example

Using the default values (length = 20 ft, width = 10 ft, depth = 4 in, density = 135 lb/ft³):

1. Convert depth to feet: 4 in ÷ 12 = 0.3333 ft
2. Calculate volume in cubic feet: 20 × 10 × 0.3333 = 66.7 ft³
3. Convert to cubic yards: 66.7 ÷ 27 = 2.47 yd³
4. Calculate weight: 66.7 ft³ × 135 lb/ft³ = 9000 lb
5. Convert to tons: 9000 ÷ 2000 = 4.5 tons

The calculator shows 66.7 ft³, 2.47 yd³, and 4.5 tons, matching the manual calculation.

What Is Type 3 Stone?

Type 3 stone is a crushed aggregate with a specified grading – typically a mix of coarse and fine particles from 1.5 inches down to dust. It is similar to Type 1 but with a slightly wider grading, making it more permeable and easier to compact in some conditions. It is commonly used as a sub-base for driveways, paths, patios, and as a drainage layer. Unlike decorative gravel, Type 3 is meant to be compacted, forming a firm, stable layer.

How to Use the Calculator

Measure the area you plan to fill in feet (or meters) and decide on the compacted depth. The calculator assumes you want the final compacted depth, not the loose depth. If you are ordering from a quarry, they usually quote in tons, so the weight output is the most important number. Always add a little extra (about 10%) to account for compaction loss, uneven ground, and spillage – the calculator does not include this automatically.

Common Mistakes & Important Details

• Mixing units: Enter length and width in feet, depth in inches. The calculator converts depth automatically, but if you use meters and centimeters, adjust accordingly.
• Compaction: The density of Type 3 stone varies from about 120 to 145 lb/ft³ depending on moisture and how well it’s compacted. The default 135 lb/ft³ is a good average, but check with your supplier.
• Depth: For a driveway, a typical compacted depth is 4-6 inches. For a path, 2-3 inches may suffice. The calculator does not tell you what depth you need – that depends on the load and ground conditions.
• Loose vs compacted volume: When delivered, the stone is loose and will settle by about 10-20% when compacted. If you order by volume, order more than the calculated compacted volume.

Comparing Type 3 to Other Aggregates

Type 3 is often compared to Type 1 (MOT Type 1). Type 1 has a tighter grading and is more commonly specified for high-load areas like road bases. Type 3 is more open and drains better, making it a good choice for french drains or as a base for permeable paving. For a simple driveway, both work, but Type 1 is the standard. If you need a decorative finish, you’d use a different material entirely, like gravel or crushed stone with a uniform size.

Cost and Ordering Tips

Type 3 stone is usually sold by the ton. Prices vary by region and quarry, but you can expect to pay roughly $20–$40 per ton. To estimate your cost, multiply the weight (tons) from the calculator by the local price per ton. Delivery fees are often separate and depend on distance and quantity. When ordering, ask for the exact density used for billing – some suppliers use 1.6 tonnes per cubic meter (about 100 lb/ft³) for loose material, which can lead to under-ordering if you don’t account for compaction.

Safety and Handling

Type 3 stone is heavy and can cause injury if handled improperly. Always wear gloves and safety glasses when moving or spreading it. Use a wheelbarrow or a machine for large quantities. When compacting, use a plate compactor and follow the manufacturer’s instructions. Be aware that fresh stone dust can be harmful if inhaled – wear a dust mask if working in a confined area.

Frequently Asked Questions

How much Type 3 stone do I need for a 10×10 ft area at 4 inches deep?

Using the calculator: 10 × 10 × (4/12) = 33.3 ft³, which is 1.23 yd³. At 135 lb/ft³, that’s about 2.25 tons. Add 10% for compaction, so order about 2.5 tons.

What is the difference between Type 1 and Type 3 stone?

Type 1 (MOT Type 1) has a tighter grading with more fines, making it more stable and less permeable. Type 3 has a wider grading and is more open, so it drains better but is slightly less load-bearing. For most driveways, Type 1 is preferred; Type 3 is often used for drainage layers or where water infiltration is needed.

How deep should Type 3 stone be for a driveway?

For a residential driveway, a compacted depth of 4 to 6 inches is typical. For heavy vehicles, go with 6 inches. The calculator lets you try different depths to see how the volume and weight change.

Does Type 3 stone compact well?

Yes, Type 3 is designed to be compacted. It contains a range of particle sizes, including fines, which interlock when compacted. However, it may not compact as tightly as Type 1 due to its more open grading. Use a vibrating plate compactor and compact in layers of no more than 4 inches.

Can I use Type 3 stone under concrete?

Yes, Type 3 can be used as a sub-base under concrete, but Type 1 is more common because it provides a more stable, level surface. If you use Type 3, ensure it is well compacted and leveled before pouring concrete.

How many tons of Type 3 stone are in a cubic yard?

That depends on the density. At 135 lb/ft³, one cubic yard (27 ft³) weighs 3645 lb, or about 1.82 tons. At 145 lb/ft³, it’s about 1.96 tons. Use the calculator with your specific density to get an accurate number.

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in length | Length | ft | 20 | 0
in width | Width | ft | 10 | 0
in depth | Depth | in | 4 | 0
in density | Density (lb/ft³) | lb/ft³ | 135 | 80
out volume_ft3 | Volume | ft³ | length * width * (depth / 12) | 1
out volume_yd3 | Volume | yd³ | (length * width * (depth / 12)) / 27 | 2
out weight_tons | Weight (US tons) | tons | (length * width * (depth / 12) * density) / 2000 | 2