How Much Gravel for a Fire Pit Area? Tons by Circle Size, Depth and Clearance

A 15-foot gravel circle around a 3-foot fire ring, 3 inches deep, is about 1.64 cubic yards (2.45 t) of stone: roughly 98 fifty-pound bags. The 15 feet comes from Junction City Fire (Ore.), which asks for a noncombustible border that wide, gravel included.

Quick pick: crushed stone 3 inches deep, ordered by the ton; check your fire district's distance rule before you dig.

Free calculator: any pad size and depth, in cubic yards, tons and truck trips: our free gravel calculator. No sign-up.

How much gravel for a fire pit area

Tons at 2 / 3 / 4 inches deep (our planning depths, based on USU's guide), using Penn State's 1.5 tons per cubic yard for #57 stone.

10 ft circle (79 sq ft): 0.73 / 1.09 / 1.45 tons

12 ft circle (113 sq ft): 1.05 / 1.57 / 2.09 tons

15 ft circle (177 sq ft): 1.64 / 2.45 / 3.27 tons

20 ft circle (314 sq ft): 2.91 / 4.36 / 5.82 tons

12 × 12 ft square: 1.33 / 2.00 / 2.67 tons

16 × 16 ft square: 2.37 / 3.56 / 4.74 tons

Cubic yards = tons ÷ 1.5.

The math, step by step

☐ Area: circle = 3.14 × radius × radius. 15 ft across: 3.14 × 7.5 × 7.5 = 177 sq ft. Square: length × width.

☐ Cubic feet = area × depth in inches ÷ 12. 177 × 3 ÷ 12 = 44 cu ft.

☐ Cubic yards = cubic feet ÷ 27 = 1.64.

☐ Tons = cubic yards × 1.5 = 2.45.

☐ Bags: 54 half-cubic-foot bags per cubic yard, or 40 fifty-pound bags per ton. 2.45 × 40 = 98.

How deep: 2, 3 or 4 inches

No fire code we found sets a gravel depth for the pad. The closest guide is USU Extension's plant-mulch sheet, which lists decorative rock as a mulch: 1 to 2 inches of fine material (under ½ in) or 3 to 6 inches of coarser material (½ to 3 in).

Our planning depths: the 2 in column for fine stone, like pea gravel (our example, not USU's); the 3 or 4 in column for coarser stone.

Weeds/landscape fabric: USU says landscape fabric under rock blocks weeds, but it's synthetic. Keep it out of the ring and well back from the fire, or skip it; fire rules ask for a border that won't burn.

How far from the house?

Rules differ by town. Three examples:

IFC 307.4.2 (2018, Knox County, Tenn.): a recreational fire, 3 ft across and 2 ft high or less, can't be within 25 ft of a structure or combustible material.

Keizer Fire District, Ore.: pit up to 3 ft wide, at least 4 in deep, sand or mineral-earth bottom; 15 ft from structures; 10 ft from property lines, fences and decks; no overhead branches.

Junction City Fire, Ore.: 15 ft from fences, decks, landscaping and structures; a 15 ft-across border of brick, gravel or damp green grass.

The distance moves the pad, not the tonnage. Gravel works for the border (Junction City), but keep round river rock out of the ring: it can explode. Call your fire department.

Before the first fire

☐ A 4-A-rated extinguisher, or dirt, sand, water or a hose, within reach (IFC 307.5).

☐ Someone stays with the fire until it's out (IFC 307.5).

☐ Dry firewood only (Junction City).

☐ Put it out completely after every use (Junction City).

☐ Skip it during burn bans.

Fire ring and extinguisher (#ad)

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Fire pit gravel FAQ

How much gravel do I need around a fire pit?

For a 15 ft circle, 1.64 cubic yards at 3 inches, about 2.5 tons.

Can I use river rock in a fire pit?

Not in the ring. Junction City Fire warns it will explode when heated.

How far should a fire pit be from a house?

25 ft under IFC 307.4.2; some districts, like Keizer, use 15 ft. Check yours.

Pavers instead? Paver calculator. More stone math: gravel driveway. Wood for the season: firewood for winter.

Watch Curb Calc on YouTube: youtube.com/@curbcalc

Sources: Junction City Fire; Keizer Fire District; Knox County, 2018 IFC; USU Extension, 2010; Penn State Dirt and Gravel Roads.