Lava rock: How Deep and How Much

Published density and depth figures for lava rock, each with its source shown — where sources disagree, we list both instead of averaging. All sources also on the methodology page.

Density (as published)

As stated	Density	Source
Red Lava Rock (1-1 1/2")	1,950 lb/cu yd	GravelShop.com product calculator
Lava Rock	1,391 lb/cu yd	CalculatorSoup Gravel Calculator density table
Lava Rock (3/8"-2"), stated as 0.65-0.9 tons/yd3	1300-1800 lb/cu yd	Inch Calculator - Stone Calculator

How deep

Use	Depth	Source
decorative/ground cover (replacing lawn area)	2 in	Roseville Rock Supply - Using Lava Rock for Landscaping

Worked example
A 100 sq ft area at 2 inches needs about 0.62 cubic yards — 0.43 to 0.60 tons depending on which cited density you use. Formula: sq ft × depth ÷ 324; tons = yards × density ÷ 2,000.

Run your own dimensions through the gravel calculator

What the sources say

A good layer of lava rock creates a barrier that weeds struggle to penetrate. Unlike organic mulch, it won't fade or decompose, holding its color over time. (Roseville Rock Supply)
Because lava rock is lightweight, it may not be the best choice in extremely windy areas where lighter materials tend to blow around. (Roseville Rock Supply)
Won't crack or explode in fire features; allows water and air to reach roots while preventing weeds and soil erosion. (Roseville Rock Supply)

Common questions

How many tons is a cubic yard of lava rock?

0.70 to 0.97 tons per cubic yard across the cited figures above. Suppliers weigh loads at the scale, so their ticket beats any table.

Why do the density figures disagree?

Moisture, stone size, and compaction all move the number, and some retail calculators reuse one site-wide default. We show each source's figure with attribution so you can see which kind of source it is.

Planning estimates from the cited figures, as of 2026-07-13. Your supplier's scale ticket and your soil conditions decide the real number.