Gravel Coverage, Depth & Tonnage: How to Calculate How Much Gravel You Need

Gravel Coverage, Depth & Tonnage: A Complete Calculation Guide

Gravel is sold by the ton or cubic yard. To order the right amount, you need to know three things: the area you're covering, the depth you want, and the density of your gravel type — so you can convert between volume and weight.

The Gravel Calculator handles all three conversions instantly. This guide explains the underlying formulas and gives you worked examples for the most common gravel applications.

The Gravel Calculation Formula

Step 1 — Volume

Volume (ft³) = Length (ft) × Width (ft) × Depth (ft)

Convert depth to feet: 2 inches = 2/12 = 0.167 ft; 4 inches = 4/12 = 0.333 ft

Step 2 — Convert to Cubic Yards

Volume (yd³) = Volume (ft³) ÷ 27

Step 3 — Convert to Tons

Weight (tons) = Volume (yd³) × Density (tons/yd³)

Gravel Density Reference Table

Gravel density (bulk unit weight) varies significantly by type, size, and moisture content. This table lists dry bulk densities — the value used for calculating order weights.

Gravel Type	Density (lb/ft³)	Density (tons/yd³)	Notes
Pea gravel (3/8")	95–105	1.28–1.42	Rounded, loose; common for walkways
Crushed granite (#57)	100–110	1.35–1.49	Angular; driveways, drainage
Crushed limestone (#57)	90–100	1.22–1.35	Lighter than granite; common in Midwest
River gravel (washed)	100–110	1.35–1.49	Rounded; decorative and drainage
Decomposed granite (DG)	105–115	1.42–1.55	Fines-heavy; compacts for pathways
#3 Coarse crushed stone	90–100	1.22–1.35	Large aggregate; drainage blankets
Crushed concrete (recycled)	70–90	0.95–1.22	Lighter than virgin aggregate
Aquarium gravel (fine)	95–105	1.28–1.42	Small particle; specific gravity ~2.65
Pea gravel (lbs per ft²)	~8 lb/ft² per inch of depth	—	Rule of thumb

Industry standard for ordering: Use 1.35 tons/yd³ as the default when the exact type is unknown. This is the commonly accepted value for standard 3/4-inch crushed stone and #57 stone — the most common driveway and drainage gravel.

Worked Example 1: Gravel Driveway

Dimensions: 12 ft wide × 60 ft long × 4 inches deep

Step 1 — Volume (ft³): 12 × 60 × (4/12) = 12 × 60 × 0.333 = 240 ft³

Step 2 — Volume (yd³): 240 / 27 = 8.89 yd³

Step 3 — Weight (tons) using crushed granite at 1.40 tons/yd³: 8.89 × 1.40 = 12.4 tons

Order 13 tons to account for minor settling and edge waste.

At $35–$ 50/ton delivered: $455–$ 650 material cost for the driveway gravel.

For driveway-specific estimates (including compaction factor), see the Gravel Driveway Calculator.

Worked Example 2: Garden Path (Pea Gravel)

Dimensions: 3 ft wide × 40 ft long × 2 inches deep

Volume (ft³): 3 × 40 × (2/12) = 3 × 40 × 0.167 = 20.0 ft³

Volume (yd³): 20.0 / 27 = 0.74 yd³

Weight (tons) at pea gravel density 1.35 tons/yd³: 0.74 × 1.35 = 1.0 ton

At 40 lbs per bag (typical home-center bag at $4–$ 6): 20.0 ft³ × 95 lb/ft³ = 1,900 lb ÷ 40 lb/bag = 47.5 bags → 48 bags

For small areas like a garden path, bagged pea gravel is often more practical than a bulk delivery.

Worked Example 3: Drainage Blanket (French Drain Trench)

Dimensions: Trench 100 ft long × 2 ft wide × 1 ft deep, with perforated pipe taking 0.12 yd³

Gravel volume: 100 × 2 × 1 = 200 ft³ - (pipe volume correction) = 200 / 27 - 0.12 = 7.41 - 0.12 = 7.29 yd³

Weight at #3 stone density 1.25 tons/yd³: 7.29 × 1.25 = 9.1 tons

Drainage stone typically costs $25–$ 45/ton. Budget $230–$ 410 for this trench.

Gravel Coverage Chart (Quick Reference)

Area coverage by volume and depth — cubic yards:

Area (ft²)	2" depth	3" depth	4" depth	6" depth
100	0.62 yd³	0.93 yd³	1.23 yd³	1.85 yd³
200	1.23 yd³	1.85 yd³	2.47 yd³	3.70 yd³
500	3.09 yd³	4.63 yd³	6.17 yd³	9.26 yd³
1,000	6.17 yd³	9.26 yd³	12.35 yd³	18.52 yd³
2,000	12.35 yd³	18.52 yd³	24.69 yd³	37.04 yd³

Tons at 1.35 tons/yd³ (crushed stone standard):

Area (ft²)	2" depth	4" depth	6" depth
500	4.2 tons	8.3 tons	12.5 tons
1,000	8.3 tons	16.7 tons	25.0 tons
2,000	16.7 tons	33.3 tons	50.0 tons

Recommended Depths by Application

The depth of gravel depends on the application's load and drainage requirements:

Application	Recommended Depth	Notes
Foot-traffic walkway	2–3 inches	Stabilized with edging
Decorative garden bed	2–3 inches	No compaction needed
Light vehicle driveway	4–6 inches	Compact in 2-inch lifts
Heavy vehicle driveway	6–8 inches	Use angular crushed stone
French drain / drainage blanket	12–18 inches	Large angular stone
Concrete subbase	4–6 inches	Compacted to 95% Proctor
Aquarium substrate	2–3 inches	Species-dependent

Pea Gravel vs. Crushed Stone — Which to Use?

Characteristic	Pea Gravel	Crushed Stone (#57)
Shape	Rounded	Angular
Compaction	Does not compact (rolls)	Compacts well
Drainage	Excellent	Excellent
Stability under traffic	Poor — rolls out from under tires	Good — locks together
Aesthetics	Attractive, natural look	More industrial
Cost	Similar	Similar
Best for	Walkways, play areas, decorative	Driveways, subbase, drainage

Never use pea gravel as a subbase under a concrete slab. The rounded particles don't compact and will shift under load, causing slab cracking. Use angular crushed stone or compacted bank run gravel for subbase applications.

For pea gravel-specific estimates, see the Pea Gravel Calculator.

Aquarium Gravel: How Much Do You Need?

Aquarium gravel is sized differently from construction aggregate and uses a different calculation — typically based on tank dimensions and desired substrate depth.

Standard guideline: 1 pound per gallon for a 1-inch-deep substrate; 2 lbs/gallon for a 2-inch substrate.

More precise calculation:

Volume (in³) = Tank Length (in) × Tank Width (in) × Depth (in)
Weight (lbs) = Volume (in³) × Density (lb/in³)

Aquarium gravel density ≈ 0.054 lb/in³ (fine gravel) to 0.062 lb/in³ (coarse)

Example — 55-gallon tank (48" × 13" × 21"), 2-inch substrate: Volume = 48 × 13 × 2 = 1,248 in³ Weight = 1,248 × 0.054 = 67 lb of gravel

See the Aquarium Gravel Calculator for instant results by tank size and substrate depth.

Gravel Cost Reference (U.S. 2025)

Product	Cost (per ton)	Cost (per yd³)
Pea gravel	$30–$ 55	$40–$ 75
Crushed granite (#57)	$35–$ 60	$47–$ 81
Crushed limestone	$28–$ 50	$38–$ 67
Decomposed granite	$40–$ 70	$54–$ 94
Washed river rock	$45–$ 80	$61–$ 108
Crushed concrete	$10–$ 25	$14–$ 34

Delivery charges typically add $50–$ 150 per truckload, plus a per-mile fuel surcharge beyond a standard radius (usually 15–30 miles). Minimum delivery is commonly 5–10 tons for bulk aggregate.

Use the Gravel Cost Calculator to estimate total material cost for any area, depth, and gravel type.

Frequently Asked Questions

How many tons of gravel do I need for a 1,000 ft² area at 4 inches deep?

Volume = 1,000 × (4/12) = 333 ft³ = 12.35 yd³. At 1.35 tons/yd³ (standard crushed stone): 12.35 × 1.35 = 16.7 tons. Order 17–18 tons to account for waste and minor settling.

How do I calculate gravel for a circular area?

Area = π × r². For a 20-foot diameter circle: Area = π × 10² = 314 ft². Multiply by depth in feet to get volume.

What does a cubic yard of gravel weigh?

Depending on type and moisture: 1.35–1.55 tons (2,700–3,100 lb) per cubic yard for most crushed stone and pea gravel. Wet gravel is slightly heavier; dry lightweight gravel like crushed concrete is lighter (~1.0–1.2 tons/yd³).

How many bags of pea gravel do I need for a 10×10 path?

10 × 10 × (3/12) = 25 ft³. At 40 lb bags with density ~100 lb/ft³: 25 × 100 = 2,500 lb ÷ 40 lb = 63 bags. Buying in bulk by the ton (25 ft³ = 0.93 yd³ × 1.35 ton/yd³ = 1.25 tons) is far cheaper for this area — order bulk if your supplier has a delivery radius that covers your address.

Use the Gravel Calculators

Standard aggregate (driveway, path, drainage): Gravel Calculator
Pea gravel: Pea Gravel Calculator
Driveway with compaction factor: Gravel Driveway Calculator
Tons-to-yards conversion: Gravel Tons to Yards Calculator
Total cost estimate: Gravel Cost Calculator
Aquarium substrate: Aquarium Gravel Calculator

Visit Concrete Calculator Max for the full suite of gravel and concrete estimation tools.