Why does lava rock weigh less than river rock?

Lava rock weighs less because the stone is porous: about 1,026 lb per yard against 2,376–2,700 lb for river rock (estimates from bag weights and one supplier).

Is landscape rock sold by the yard or by the ton?

Landscape rock is sold both ways: supply yards list some rock per cubic yard and some per ton. Enter the volume, pick the rock type, and the calculator gives both cubic yards and tons.

Rock Calculator

Landscape rock weighs 1,026–2,700 lb per cubic yard depending on the rock type. Pick the rock, then enter length, width and depth below to get yards, tons, bags and cost.

Material

Area

Length ft

Width ft

Count

Depth in

Order options No waste · ¼ yd steps · reference price

Extra for waste

Supplier sells by

Your price $ per yd³, optional

Know the tons? Supplier quote in tons → yards

Tons

Tape readings work: 10' 6", 10 1/2, 10½ or 10.5. Depth takes inches or feet (1 ft). Areas add up. Other material? Use the cubic yard calculator.

Order Estimate

0.75 cubic yards to order

rounded up to the nearest ¼ yd³

Each cube is 1 yd³ (3 × 3 × 3 ft). Solid: exact 0.56 yd³. Order: ¾ of a yard.

Exact 0.56 yd³ · 15 ft³ · 0.42 m³

At 2 in deep, 1 yd³ covers 162 ft².

Weight: 0.89–1.01 tons (loose, varies with stone size)
Bags: 30 × 0.5 cu ft
Trucks: 1–2 pickup loads (half-ton class)
Cost: $41–$60

Compare with bags

Price per 0.5 cu ft bag, $

You need 0.75 cubic yards of river rock ≈ 0.89–1.01 tons (loose, varies with stone size) ≈ 30 bags of 0.5 cu ft.

Suppliers sell by the ¼, ½ or whole yard, often with a minimum order — round up to your supplier's step.

Order sheet for your supplier

River rock weight: loose, varies with stone size (Smoky Mountain Sand & Gravel). Cost: reference range, pickup at two supply yards (OH, WA) (supplier price lists, 2026); local prices vary.

Landscape rock weight by rock type

Landscape rock has no single weight per cubic yard: lava rock weighs about 43% as much as river rock, well under half.

Landscape rock weight per cubic yard
Material	lb per yd³	tons per yd³	Bags
River rock^*	2,376–2,700	1.19–1.35	0.5 cu ft
Lava rock^*	1,026	0.51	0.5 cu ft
Decomposed granite^*	2,400–2,700	1.2–1.35	0.5 cu ft
Pea gravel^*	2,600–2,700	1.3–1.35	0.5 cu ft (50 lb)
Crushed stone	2,600–2,700	1.3–1.35	Bulk only

Weight basis: river rock loose, varies with stone size; lava rock from one 0.5 cu ft bag weight; decomposed granite loose, as sold; pea gravel loose, typical; crushed stone loose, as delivered. * Estimate: supplier data or one source only. Sources: Smoky Mountain Sand & Gravel; Lowe's; MRM Landscape Supply (WA); Tri-State Landscape Supply (OH); HomeGuide; Sutherland Landscape (Chico, CA); Outdoor Warehouse Supply (TX); Western Materials (Valencia, CA); Earth Stone Rock (CA/AZ); Southwest Boulder & Stone; AreA Landscape Supply (Mokena, IL); Sequoia Landscape Materials (Santa Rosa, CA); Kafka Granite; Caterpillar; Vulcan Materials; USDA-NRCS.

Choose the exact rock in the calculator, because one "landscape rock" figure would be off by up to 0.84 tons per yard.

Rock worked example: 15 × 6 ft planting bed

A 15 × 6 ft planting bed at 2 in deep takes 0.75 cubic yards of rock, whatever the type; the tons change with the rock.

Area15 ft × 6 ft90 ft²
Volume90 ft² × 2 in ÷ 1215 ft³
Cubic yards15 ft³ ÷ 270.56 yd³
Ordernext ¼ yard up0.75 yd³
River rock× 2,376–2,700 lb0.89–1.01 tons
Lava rock× 1,026 lb0.38 tons

Round stone for creek beds and borders has its own river rock calculator.

Landscape rock FAQ

Why does lava rock weigh less than river rock?: Lava rock weighs less because the stone is porous: about 1,026 lb per yard against 2,376–2,700 lb for river rock (estimates from bag weights and one supplier).
Is landscape rock sold by the yard or by the ton?: Landscape rock is sold both ways: supply yards list some rock per cubic yard and some per ton. Enter the volume, pick the rock type, and the calculator gives both cubic yards and tons.