By Zencalcy Editorial TeamLast reviewed About us
Fire glass is sold by weight in 10 lb bags, but coverage depends on depth. A 2-inch layer is the usual finish over a burner; deeper looks richer but blocks gas flow and wastes glass. This calculator converts your pit diameter into pounds and bags.
How much fire glass fills your fire pit or fireplace.
V = L × W × D W = V × ρ Cost = V × price
Bulk density is taken as 1,600 kg/m³ (about 100 lb per cubic foot), typical for ½-inch tempered fire glass. Round bags up; a partial bag cannot be topped up from the same dye lot later.
| Symbol | Meaning |
|---|---|
| L, W | Length and width of the area being covered. |
| D | Spread depth of the material. |
| V | Volume in cubic yards (and cubic metres). |
| ρ | Bulk density of the material. |
| W | Total weight, shown in pounds and US tons. |
A 30 in circle is 4.9 sq ft, so a 2-inch layer needs 0.82 cu ft — about 82 lb, or nine 10 lb bags.
Continue with the Gravel Calculator, Sand Calculator, Rock Calculator, or the River Rock Calculator — or browse more materials & quantities and all construction calculators.
One and a half to two inches over a ring or pan burner is standard. More than 2 inches restricts gas mixing and can produce soot.
Results use standard construction estimating arithmetic: volumes from measured area and depth, unit weights from published material densities, and code-referenced spans or clearances where the page names a code. Quantities are rounded up to whole saleable units and include the stated waste allowance. These tools are planning aids, not structural design, and do not replace a licensed engineer, a local code check, or a contractor's site measurement.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026