Gravel Mulch Calculator
Calculate gravel mulch in tons or cubic yards. Includes pea gravel and decorative gravel presets.
Gravel Mulch Calculator
Tons and cubic yards for pea, crushed, and river gravel
Gravel Types
Gravel mulch comes in three main types: pea gravel, crushed gravel, and river gravel. Pea gravel is small (1/4 to 3/8 inch), rounded, and used for pathways and beds. Crushed gravel is angular and locks together for driveways and drainage. River gravel is smooth and decorative. The Mulch and Soil Council (MSC) classifies all three as inorganic mulch. Pea gravel weighs about 100 lbs per cubic foot, or 1.35 tons per cubic yard.
Color and stone size guide the choice. Pea gravel comes in tan, brown, and gray blends that suit pathways and play areas. Crushed gravel in 3/4 inch size packs tight for driveways and french drains. River gravel in 1 to 3 inch stones gives a decorative finish around water features and dry creek beds. Larger stones resist scattering on slopes. Smaller pea gravel feels softer underfoot but rolls more on inclines. Match the stone size to the use: fine gravel for comfort, coarse gravel for drainage and slope stability.
Tons by Bed Size
Gravel suppliers sell by the ton for delivery and by the cubic yard for volume. One cubic yard of pea gravel weighs 1.35 tons. The table below shows tons needed for common bed sizes at the standard 3 inch depth. Multiply by 1.5 for 2 inch depth or by 0.75 for 4 inch depth.
| Bed Size | Cubic Yards (3") | Pea Gravel Tons | 50 lb Bags |
|---|---|---|---|
| 100 sq ft | 0.93 yd³ | 1.25 tons | 50 bags |
| 250 sq ft | 2.31 yd³ | 3.1 tons | 125 bags |
| 500 sq ft | 4.63 yd³ | 6.25 tons | 250 bags |
| 1,000 sq ft | 9.26 yd³ | 12.5 tons | 500 bags |
Depth Recommendations
Gravel mulch needs 2 to 3 inches of depth for decorative beds over landscape fabric. Pathways need 3 to 4 inches for foot comfort. Soft base soil needs 4 to 6 inches for a stable pea gravel path. Gravel settles 20 to 25 percent after rain and foot traffic, so a 3 inch loose layer compacts to about 2.4 inches. Spread 3.7 inches loose to finish at 3 inches.
How does the gravel mulch calculator work?
The gravel mulch calculator uses the formula Length x Width x Depth in inches / 324 = Cubic Yards. It then multiplies cubic yards by the weight factor to get tons. A 20 x 10 ft bed at 3 inches deep is 1.85 cubic yards or 2.5 tons of pea gravel. The calculator also outputs 50 lb bag count for small bagged orders.
Why use gravel mulch instead of wood mulch?
Gravel mulch lasts 20 plus years without replacement. Wood mulch breaks down in 1 to 4 years. Gravel suits hot, dry climates and xeriscape gardens. It does not improve soil health and retains heat in summer. Choose gravel for permanent low-maintenance beds and wood mulch for soil-building plant beds.
How to Install Gravel Mulch
Gravel mulch installs in five steps over one weekend. Clear the bed of weeds and rake the soil level. Lay commercial woven landscape fabric and pin the edges every 2 feet. Install steel or stone edging at least 4 inches tall to hold the gravel. Pour the gravel and rake it to an even depth. Compact lightly with a hand tamper so the surface locks. A 500 sq ft bed takes one person about 4 hours.
Edging matters most on slopes and along lawns. Gravel migrates without a hard border, spilling into grass and beds. Steel edging lasts 20 plus years and resists frost heave. The National Association of Landscape Professionals (NALP) lists edging and fabric as the two required underlayers for any permanent gravel install. Top up the gravel by half an inch every few years as it settles and scatters.
FAQ
A 500 sq ft bed at 3 inches deep needs 4.63 cubic yards or 6.25 tons of pea gravel. That equals about 250 fifty-pound bags. Order 5 cubic yards to cover the 10 percent buffer.
Pea gravel weighs 1.35 tons per cubic yard. Crushed gravel weighs 1.4 tons. River gravel weighs 1.45 tons. A half-ton pickup truck holds about 0.5 cubic yards of gravel safely.
Pea gravel needs 2 to 3 inches for decorative beds and 3 to 4 inches for pathways. Soft base soil needs 4 to 6 inches. Add 0.7 inches extra for 20 to 25 percent compaction loss.
Gravel mulch needs woven landscape fabric underneath. Without it, soil mixes into the gravel within two years and weeds grow through. The NALP lists fabric as mandatory under decorative gravel.
One ton of gravel covers 240 sq ft at 1 inch, 120 sq ft at 2 inches, 80 sq ft at 3 inches, and 60 sq ft at 4 inches deep. Depth is the biggest variable in coverage.
Crushed gravel is the best gravel for drainage because angular edges lock and let water pass. River gravel works for French drains. Pea gravel suits decorative beds and light pathways, not heavy drainage.
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