Building a driveway, filling a French drain, putting in a gravel patio - the first question is always: how much material do I actually need?

Order too little and you're making extra trips. Order too much and you're wasting money. This guide gives you the formulas, tables, and rules of thumb to get it right.

The Quick Formula

For rectangular areas:

Cubic Yards = (Length × Width × Depth) ÷ 27

(All measurements in feet. Divide inches by 12 to convert to feet.)

To convert to tons:

Tons = Cubic Yards × 1.4

(Crushed stone/RCA averages about 1.4 tons per cubic yard)

Quick Reference Tables

Coverage by Depth (per ton of material)

| Depth | Square Feet Covered | |-------|---------------------| | 1 inch | 240 sq ft | | 2 inches | 120 sq ft | | 3 inches | 80 sq ft | | 4 inches | 60 sq ft | | 6 inches | 40 sq ft |

Common Project Estimates

| Project | Typical Depth | Tons per 100 sq ft | |---------|--------------|---------------------| | Driveway base | 4-6 inches | 1.5-2.5 tons | | Driveway surface | 2-3 inches | 0.8-1.2 tons | | Walkway | 2-4 inches | 0.8-1.5 tons | | French drain | 6-12 inches | 2.5-5 tons | | Patio base | 4 inches | 1.5 tons | | Decorative beds | 2-3 inches | 0.8-1.2 tons |

Step-by-Step Calculation

Step 1: Measure Your Area

Rectangular/Square Areas:

Length in feet × Width in feet = Square feet

Circular Areas:

Radius × Radius × 3.14 = Square feet

Irregular Areas:

Break into rectangles/triangles
Calculate each section
Add together

Step 2: Determine Depth

Recommended depths by project:

| Application | Minimum Depth | Recommended Depth | |-------------|--------------|-------------------| | Light foot traffic | 2 inches | 3 inches | | Heavy foot traffic | 3 inches | 4 inches | | Vehicle traffic | 4 inches | 6+ inches | | Drainage/French drain | 6 inches | 8-12 inches | | Base layer (under concrete/asphalt) | 4 inches | 6 inches |

Step 3: Calculate Volume

Formula:

Square Feet × Depth (in feet) = Cubic Feet Cubic Feet ÷ 27 = Cubic Yards

Example:

Driveway: 12' wide × 60' long = 720 sq ft
Depth: 4 inches = 0.33 feet
Volume: 720 × 0.33 = 237.6 cubic feet
Cubic yards: 237.6 ÷ 27 = 8.8 cubic yards

Step 4: Convert to Tons

Different materials have different weights:

| Material | Tons per Cubic Yard | |----------|---------------------| | Crushed limestone | 1.35 | | Crushed granite | 1.40 | | Recycled concrete (RCA) | 1.35-1.40 | | Pea gravel | 1.35 | | River rock | 1.30 | | Crusher run | 1.50 |

Example (continued):

Cubic yards: 8.8
Material: RCA (1.4 tons/yard)
Total: 8.8 × 1.4 = 12.3 tons

Step 5: Add Buffer

Always order 5-10% extra for:

Uneven subgrade
Compaction (material settles)
Spillage
Future repairs

Final order: 12.3 × 1.10 = 13.5 tons (round up to 14 tons)

Real-World Project Examples

Example 1: Single-Car Driveway (10' × 50')

| Layer | Depth | Tons Needed | |-------|-------|-------------| | Base (2" stone) | 4" | 5.2 tons | | Surface (3/4" stone) | 2" | 2.6 tons | | Total | 6" | 7.8 tons |

With 10% buffer: Order 8.5-9 tons

Example 2: Two-Car Driveway (20' × 60')

| Layer | Depth | Tons Needed | |-------|-------|-------------| | Base layer | 4" | 15.5 tons | | Surface layer | 2" | 7.8 tons | | Total | 6" | 23.3 tons |

With 10% buffer: Order 25-26 tons

Example 3: French Drain (50' × 2' × 2' deep)

Volume: 50 × 2 × 2 = 200 cubic feet
Cubic yards: 200 ÷ 27 = 7.4 yards
Tons (3/4" drainage stone): 7.4 × 1.4 = 10.4 tons

With buffer: Order 11-12 tons

Example 4: Patio Base (12' × 16')

| Layer | Depth | Tons Needed | |-------|-------|-------------| | Compacted base | 4" | 4.5 tons |

With buffer: Order 5 tons

Adjusting for Compaction

Crushed materials compact 10-15% when properly installed. Two ways to handle it:

Approach 1: Order extra

Calculate exact need
Add 10-15% to the final number

Approach 2: Adjust depth calculation

Want 4" finished depth?
Calculate for 4.5" loose depth

Most suppliers expect you to order a little more than calculated. Standard practice.

Delivery Considerations

Dump Truck Capacities

| Truck Type | Typical Load | |------------|-------------| | Single axle | 8-10 tons | | Tandem axle | 15-20 tons | | Tri-axle | 20-25 tons | | Semi (belly dump) | 22-26 tons |

Cost Factors

Material cost: $15-$50 per ton
Delivery fee: $50-$150+ depending on distance
Minimum order: Many suppliers require 3-5 ton minimum

Ordering Tips

Order full truck loads when possible - partial loads still hit you for the full delivery fee
Combine orders - base and surface in one delivery saves money
Get multiple quotes - prices vary a lot between suppliers
Ask about overage policy - some suppliers take back unused material

Different Materials, Different Coverage

Not all aggregates cover the same:

Lightweight Materials (More Coverage per Ton)

Lava rock
Pumice
Decorative bark mulch

Heavy Materials (Less Coverage per Ton)

Crusher run (dense graded)
Slag
Iron ore aggregate

Standard Materials

Crushed limestone
Crushed granite
Recycled concrete (RCA)
Pea gravel

Common Mistakes to Avoid

1. Forgetting About Slope If your driveway has a crown (higher in middle), you'll need extra material for the raised center.

2. Not Accounting for Soft Spots Muddy areas or soft soil may need extra base material.

3. Mixing Up Cubic Yards and Tons Suppliers sell by the ton. Calculators often give cubic yards. Don't forget to convert!

4. Ignoring Delivery Access Can a dump truck access your property? Tight spots may require smaller trucks (at higher per-ton cost).

5. Underestimating Long Driveways That 200' driveway you eyeballed? Actually measure it. Visual estimates are usually wrong.

Printable Worksheet

Project: ________________

Measurements:

Length: _____ feet
Width: _____ feet
Depth: _____ inches (÷ 12 = _____ feet)

Calculations:

Square feet: _____ × _____ = _____
Cubic feet: _____ × _____ = _____
Cubic yards: _____ ÷ 27 = _____
Tons: _____ × 1.4 = _____
Plus 10% buffer: _____ × 1.10 = _____

Order: _____ tons of _____________

Need crushed stone or RCA delivered? Call SMSG at (865) 999-0857 for free quotes. We deliver throughout Blount County, Maryville, Alcoa, and the surrounding East Tennessee area, and we'll help you calculate exact quantities.

Or use our interactive Gravel Calculator to run the numbers yourself.

RCA & Gravel Calculator: Tons You Need for Driveways & Patios