The complete stone and gravel guide

Aggregate is sold three different ways

Stone is quoted by the ton, by the cubic yard, or by the bag, and the three do not convert cleanly because the conversion depends on the product. Most crushed stone runs 1.3-1.5 tons per cubic yard; screened topsoil and mulch are lighter; wet sand and dense-graded base are heavier.

The number that matters at ordering time is coverage: how many square feet one ton covers at your chosen depth. For typical crushed stone at about 1.4 tons per cubic yard, one ton covers roughly 100 square feet at 2 inches, 80 at 2.5 inches, and 65-70 at 3 inches.

Bagged stone is the most expensive way to buy aggregate by a wide margin — usually three to five times the bulk price per ton — and is only sensible below about half a cubic yard.

The coverage maths

Volume first: area in square feet times depth in feet gives cubic feet, divided by 27 gives cubic yards. Multiply cubic yards by the product's tons-per-yard figure to get tonnage.

A 20 × 30 ft gravel area at 3 inches is 600 sq ft × 0.25 ft = 150 cubic feet = 5.56 cubic yards. At 1.4 tons per yard that is about 7.8 tons.

Add 5-10% for compaction and spreading loss on a driveway, and expect dense-graded base products to lose 20-25% of loose depth under a plate compactor.

• Cubic yards = sq ft × depth (in) ÷ 12 ÷ 27
• Tons = cubic yards × tons per yard (1.3-1.5 for most crushed stone)
• One ton of crushed stone ≈ 100 sq ft at 2 in depth

Decoding product names

Numbered sizes come from the ASTM/AASHTO gradation system. Lower numbers are larger stone. #57 is roughly 3/4 inch clean stone, the general-purpose drainage and base aggregate. #8 is 3/8 inch chip, used for paver bedding in open-graded systems. #4 is 1.5 inch, used for heavy drainage and rip rap transitions.

Regional names cover the same materials: crusher run, DGA, 21A, ABC and road base are all dense-graded aggregate with fines. Stone dust, screenings, decomposed granite and manufactured sand are the fines fraction on its own.

The single most useful distinction is clean versus dense-graded. Clean stone (all one size, no fines) drains and does not compact into a slab. Dense-graded stone (full range down to dust) compacts into a rigid load-bearing layer and holds water. Use clean for drainage, dense-graded for base.

Depth by application

Decorative beds and mulch replacement: 2 inches over landscape fabric, 3 inches if you want full weed suppression. Walkways: 2-3 inches over a compacted sub-base.

Gravel driveways: 4 inches of #3 or crusher run sub-base, then 3 inches of dense-graded top course, refreshed every few years. Building one 8-inch layer in a single pass produces a soft driveway; two compacted layers of different gradation produce a firm one.

French drains and drainage trenches: fill with clean #57 stone, never dense-graded, and wrap in geotextile so soil fines cannot silt up the void space.

Ordering and delivery

A standard tandem dump truck carries 10-14 tons; a tri-axle 16-20. Delivery is priced per load, so ordering 6 tons costs nearly what 12 does — worth knowing when a job sits near a truck boundary.

Ask where the truck can tip. Most drivers need overhead clearance and a firm, level surface, and a pile dropped in the wrong place turns into hours of wheelbarrow work.

Order slightly over rather than under. A second short-load delivery usually costs more than the extra ton you did not need.

Where to go next

The guides below break down coverage and depth by application, how to pick a gravel type for a specific job, the weight and unit conversions that trip people up, and how to build a drainage trench that keeps working.

Density and coverage by product

Approximate. Ask your yard for their figure — it varies with moisture and source rock.

Recommended depth by application