Pea Gravel Calculator

Pea gravel is rounded stone, bought in bulk by the ton or in bags by volume. Loose gravel weighs 1.4 tons per cubic yard, and a short ton is 2,000 lb. The tons figure uses that general gravel weight, so compare it with your supplier's figure for pea gravel. Each bag in the count holds 0.5 cu ft, so read the volume printed on the bag you buy.

How to use this calculator

1. Pick the shape that fits the spot. Rectangles suit paths, strips and beds, circles suit round seating pads, triangles fill corners and a ring fits a tree surround.
2. Enter the length and width, or the diameter, then the depth. Depth changes the result in the same proportion as length and width, so settle the depth before you enter the rest.
3. For a tree ring, enter the outside diameter in the diameter field and the inside diameter in the inside diameter field. The inside circle is the trunk area that gets no stone.
4. Compare the bag count with the bulk figure. Bags suit a single bed or a few steps, while a path or seating area is easier with bulk delivery.
5. Enter the price per ton to see the material cost. Edging, a weed barrier and delivery are not included.

Worked examples

Cubic yards of pea gravel for common bed, path and pad sizes

Cubic yards, exact volume without extra for waste.

How deep should the layer be?

Depth decides whether the soil underneath stays hidden and whether the stones stay put. A thin layer shows bare patches soon, because stones scatter underfoot and get raked toward the edges. A deeper layer covers better and lasts longer between top-ups, but it uses more stone and is heavier to haul.

Choose the depth by the job rather than by habit. A decorative path or a bed around plants is well covered by a modest layer. A surface that people run and play on has its own depth requirements, so read the equipment or surfacing specification first.

Bags or bulk?

Bags work for a single bed, a few steps or a patch that needs topping up. The count uses 0.5 cu ft per bag, the yield of all-purpose gravel, so compare it with the volume on your bag.

For a path, a seating area or any job bigger than a few bags, bulk delivery is usually easier. Plan where the truck can drop the load, and move the pile in small wheelbarrow loads.

Edging and tree rings

Pea gravel moves. Foot traffic, rain and mowers push stones onto lawns and into beds unless the edge holds them. Set the edging before you spread the stone: a metal or plastic strip level with the finished surface, or a row of pavers.

Around a tree, lay the stone in a ring and keep it back from the trunk. Check with your local extension office for the distance, because it depends on the species and the site.

• Skipping edging on a slope. Stones roll downhill and collect at the bottom, so set a retaining edge on the low side first.
• Using the outside diameter alone for a tree ring. Without the inside diameter, the calculator counts stone where the trunk stands.
• Spreading stone over bare soil with no weed barrier. Weeds can grow up through a thin layer, which is why many gardeners lay a barrier first.

How the calculation works

Convert each measurement to feet, find the area of the shape, and multiply by the depth. A ring's area is the outer circle minus the inner one, and a triangle is half of the rectangle with the same base and height.

The tons figure converts the volume with the weight of loose gravel, 103.7 lb per cubic foot. Stone size and packing change that weight, so treat the tons figure as an estimate.

Common questions