aggregates · sold by the cubic yard and by the ton
Landscape Rock Calculator
Type the bed you are covering and how deep the stone goes. The result comes back in the two units landscape rock is sold in — cubic yards and tons.
What to order
1.23cubic yards
or0.74tons, loose
8 ft short side15 ft long side
Both figures are for Lava rock loose, the state it is in when it is delivered and spread.
The formula, written out
(15 ft × 8 ft × 3 in ÷ 12) × (1 + 10% waste) ÷ 27 = 1.23 cubic yards
1.2222 cubic yards × 1200 lb per cubic yard (loose) ÷ 2000 = 0.74 tons
The formula above is the one that produced the numbers: the page asks for both in the same call, so the two cannot drift apart.
A bed 15 ft by 8 ft at 3 inches deep is 30 cubic feet of stone. Adding the 10% waste factor makes 33 cubic feet, which is 33 ÷ 27 = 1.23 cubic yards. At 1,200 pounds per cubic yard that is about 1,467 pounds, or 0.74 tons — one of the few loads on this site a pickup will actually take.
measured loose · read 2026-08-15 · next check 2027-08-15
“Sold by the Ton (2,000 lbs.) (1 Cu. Yard = Approximately 1,200 lbs.)”
Suburban Landscape Supply, red lava rock · read 2026-08-15
“Weight per Yard: 1200 lbs”
Main's Landscape Supply, black lava (aka black mesita, lava rock) · read 2026-08-15
“Weight per Cubic Yard ~ 1,550 lbs.”
North Bay Materials, lava rock (Red Hills, and Burnt Rose at the same figure) · read 2026-08-15
Your supplier has the last word. Aggregates vary by quarry and soil varies by the week it was dug, so the range above is what to expect and not a promise about the load you are buying. The weight on their ticket is the one you pay for.
One stone is offered here today, and that is what has been sourced rather than what the page is for. A decorative stone earns a place on this page once its weight has been read from three independent yards, and it leaves this page the day it gets a calculator of its own.
Why is lava rock so much lighter than other landscape rock?
Because it is full of holes. Volcanic rock cools with gas trapped in it, so a cubic yard weighs about 1,200 pounds against roughly 2,700 for river rock — less than half. That is why it is sold by the cubic yard almost everywhere and why one person can spread a yard of it in an afternoon. It also floats away in heavy runoff, which river rock does not.
Where is the river rock option?
On its own page. River rock is the one decorative stone here with a calculator of its own, so it is answered there rather than twice — the same number in two places eventually becomes two different numbers. This page is for the stones that do not have their own page.
How deep should decorative rock go in a bed?
Two to three inches over landscape fabric is the usual figure for a bed you are not walking on, and 3 inches is what this page defaults to. Deeper does not suppress more weeds and it costs proportionally more. Around a downspout or in a dry creek bed you will want more, and larger stone.
Should I order by the ton or by the cubic yard?
Both are given above. For light stone like lava rock the cubic yard is the safer unit to think in, because a ton of it is an enormous pile and a ton of a dense stone is a small one — the two units are much further apart here than they are on the crushed stone page.