How much gravel do I need for a circle?

Volume in cubic feet = π × (diameter ÷ 2)² × depth (depth in feet). For a 10 ft diameter circle at 3 inches deep: π × 25 × 0.25 = 19.6 cuft = 0.73 yd³. Multiply by your material's density (lb/yd³) and divide by 2,000 for tons.

Should I enter diameter or radius in the calculator?

Diameter — the full distance edge-to-edge across the circle. The calculator handles the radius squaring internally. Entering radius by mistake quadruples your estimate.

How much gravel for a fire pit area?

For a typical 10–12 ft diameter fire-pit gravel pad at 3 inches deep, you need 0.7–1.0 cubic yards or roughly 1 ton of pea gravel. Add another ton if you want a wider safe zone.

How much rock do I need to go around a 3-foot circle?

For a 1-foot-wide gravel ring around a 3-foot-diameter circle (like a small fire pit) at 3 inches deep, you need about 12.5 sq ft of coverage — roughly 0.12 cubic yards, or about 285 lbs (0.14 ton) of pea gravel. Method: take the outer circle (5 ft across here), subtract the inner circle (3 ft), and multiply the leftover ring area by your depth. Widen the band or the depth and the weight climbs fast.

How much does a circle of gravel weigh?

Weight = area × depth × density. A filled circle at 3 inches of pea gravel weighs about 160 lbs at 3 ft across, 0.32 ton at 6 ft, 0.89 ton at 10 ft, and 1.28 tons at 12 ft. Swap pea gravel (2,450 lb/yd³) for heavier crushed stone or river rock (2,550 lb/yd³) and add about 4%.

How do I calculate gravel for a ring or donut shape?

Use annulus mode on the main Gravel Calculator. Enter outer diameter and inner diameter; the calculator subtracts the inner area automatically. Useful for gravel rings around tree wells, fire pits, or fountain features.

What's the right depth for a circular gravel patio?

4 inches over a compacted base for a loose-gravel patio you walk on. 4 inches base + 1 inch sand if you're laying pavers on it. 2–3 inches for purely decorative ground cover (like the ring around a fire pit).

How much gravel for a tree ring?

A typical 4 ft diameter ring with a 1 ft tree-trunk well (annulus from 4 ft outer to 1 ft inner) at 3 inches deep needs about 0.34 cuft, or about 50 lbs of pea gravel — one good-sized retail bag.

Do I need to enter radius or diameter?

Diameter — measure the longest distance edge to edge through the center of the circle. The calculator handles π(r²) internally. If you measured the radius instead, just multiply by 2 before entering. For an irregular oval, average a few diameter measurements at different angles for a usable estimate.

How do I calculate gravel for a half-circle or quarter-circle?

Calculate the full circle, then divide. A half-circle needs half the volume; a quarter-circle needs one-quarter. So a 10-foot-diameter circle at 4 inches deep = 0.97 yd³ → half-circle = 0.49 yd³, quarter = 0.24 yd³. For complex shapes that mix arcs and rectangles, use Multi-area mode on the main calculator and add each piece separately.

Circle Gravel Calculator — Yards & Tons

How this calculator works for circles

A circle's volume is π × (diameter/2)² × depth. The calculator handles π and the squaring for you — you just enter the diameter (the widest distance across the circle, edge to edge) and the depth.

Don't enter the radius by mistake. If you measure radius (center to edge), double it before typing. A 6 ft radius circle has a 12 ft diameter — a 4× difference in area if you mix them up.

The pi shortcut

For a quick mental check: a circle's area is roughly 0.785 × diameter². A 10 ft circle is about 78 sq ft; a 12 ft circle about 113 sq ft. Useful when comparing fire-pit sizes at the supply yard.

Common circle sizes at a glance

Gravel to fill a solid circle at 3 inches of pea gravel (2,450 lb/yd³). These are the sizes people actually search for — a 3-foot tree well, a 6-foot focal bed, a 10- or 12-foot fire-pit pad.

Gravel to fill a full circle at 3 inches deep, pea gravel.
Diameter	Area	Volume @ 3"	Pea gravel @ 3"
3 ft	7 sq ft	0.07 yd³	~160 lb (0.08 ton)
6 ft	28 sq ft	0.26 yd³	~0.32 ton
10 ft	79 sq ft	0.73 yd³	~0.89 ton
12 ft	113 sq ft	1.05 yd³	~1.28 ton

For a ring of gravel around a fire pit rather than a filled circle, subtract the inner circle from the outer — or use annulus mode on the main calculator, which does the subtraction for you.

Recommended depth & material

Use	Depth	Material	Notes
Around a fire pit (decorative ring)	3"	Pea gravel or river rock	Ring shape: use annulus mode on home calc.
Tree well (mulch ring)	2" – 3"	Pea gravel or river rock	Keep 2" ring away from trunk.
Circular patio (loose gravel)	4"	#57 base or pea gravel top	Edge to keep stones contained.
Round paver patio	4" base + 1" sand	CA6 base, concrete sand bedding	See paver-base for two-layer math.
Round French drain (catch basin)	12"	#57 washed	Around a perforated catch basin.

How to measure a circle

Measuring circles is straightforward — just be precise about diameter vs. radius.

Stake the center. Drive a stake at the dead center of the planned circle. Tie a string to it.
Set the radius with the string. Mark the desired radius on the string (half the diameter you want). Pull the string taut and walk a circle, marking with chalk or paint.
Measure the diameter to confirm. Use a tape across the widest part of the marked circle. Verify it matches twice your intended radius.
Enter the diameter in the calculator. Diameter, not radius. The calculator squares the radius internally — you'd be inflating your estimate by 4× if you typed the radius.
Set depth and material. 3 inches of pea gravel is the default for a decorative circle. Adjust per use case.
Add 10% buffer. Circles waste a tiny bit more material than rectangles because the edge isn't a clean line.

Worked example: 12-ft circular gravel area, 3" deep

A small circular patio or fire-pit area: 12 ft diameter, 3 inches deep, pea gravel.

Area: π × (12/2)² = π × 36 = 113 sq ft
Volume: 113 × 3 ÷ 324 = 1.05 yd³
Weight: 1.05 × 2,450 ÷ 2,000 = 1.29 tons
With 10% buffer: ~1.4 tons of pea gravel.
Cost: at $55/ton, ~$77 in stone, plus delivery. Or 65 retail bags (0.5 cuft) at ~$5 each = $325 if you go bagged.

Bigger circle? At 16 ft diameter, area jumps to 201 sq ft, and the order roughly doubles to ~2.5 tons.

Circular Gravel Calculator

Circular gravel calculator

How this calculator works for circles

Common circle sizes at a glance

Recommended depth & material

How to measure a circle

Worked example: 12-ft circular gravel area, 3" deep

Frequently asked questions

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