LayoutWise

Gravel, Landscape Rock & Mulch Calculator

Pick the stone or mulch, set the depth, and add each bed, path or tree ring. You get cubic yards for a bulk order, tons, the number of bags, and the fabric and edging to go with it.

Your project

1. Material
2. Areas

Break an odd-shaped bed into rectangles, circles and triangles — they're added together.

Length
ft
in
Width
ft
in
Length
ft
in
Width
ft
in
3. Extras

Volume

1.87 cu yd

order 2 cu yd

Weight

2.52 tons

1.35 t per cu yd

Bags

101

0.5 cu ft (≈50 lb)

Fabric

2 rolls

3' x 50'

Order bulk. This many bags is several heavy trips and usually costs more.

Your areas

192 sq ft total
72 sq ft120 sq ft
3"Pea gravel over landscape fabric, held in by edging

Shopping list

  • ✓Pea gravel: 1.87 cu yd (50.4 cu ft, incl. 5% extra)
  • ✓Bulk order: about 2.52 tons (2 cu yd) — or 101 bags of 0.5 cu ft (≈50 lb)
  • ✓Landscape fabric: 2 rolls of 3' x 50' (230 sq ft with 6" overlaps)
  • ✓Landscape staples: 59 (one every 3 ft along edges and seams)
  • ✓Edging: 98 ft (6 x 20 ft lengths)

Weights use typical loose densities; stone from your supplier can be 10% lighter or heavier, and many yards sell by the ton. Building a driveway or paver base? See the paver calculator for base and sand layers.

How much gravel do I need?

Multiply the area in square feet by the depth in feet to get cubic feet, then divide by 27 for cubic yards. Depth in inches ÷ 12 gives feet. Example: a 20' x 10' bed at 3 inches is 200 x 0.25 = 50 cu ft, or 1.85 cubic yards.

Odd shapes are easiest split into simple pieces: a curved bed is roughly a rectangle plus half a circle, and a ring around a tree is a circle with the middle taken out. Add the pieces together.

Cubic yards to tons

Quarries and landscape yards often sell stone by the ton, so you need the weight too. Typical loose weights per cubic yard:

MaterialTons per cu ydUsual depth
Pea gravelabout 1.352–3" (paths and beds)
#57 crushed stoneabout 1.43–4" (driveway top, drainage)
Crusher run / road baseabout 1.54–8" (compacted base)
River rockabout 1.352–4" (larger stones need more)
Decomposed graniteabout 1.42–4" (compacted paths)
Lava rockabout 0.62–3"
Wood mulchabout 0.42–3"

Weights change with the stone's source and how wet it is, so treat them as a planning number and confirm with your supplier. In the example above, 1.85 cubic yards of pea gravel is about 2.5 tons.

Compaction and extra

Stone that gets tamped or driven on settles into a smaller volume. Crushed stone and road base are ordered with an allowance — the calculator adds 10% for #57 stone, 15% for decomposed granite and 20% for road base when you say it will be compacted. Rounded stone like pea gravel and river rock barely compacts. A further 5% covers uneven ground and spillage.

Bags or bulk?

Most bagged gravel is half a cubic foot (about 50 lb), so one cubic yard is 54 bags. Below about three-quarters of a yard, bags are usually simpler. Above a yard and a half, a bulk load is almost always cheaper and saves many trips, even with a delivery fee. Bagged mulch is usually 2 cu ft, or about 14 bags to the yard.

How deep should mulch be?

University extension services recommend 2 to 3 inches of wood mulch, counting what's left from previous years, and keeping it a few inches back from tree trunks and plant stems. Deeper mulch keeps air and water from the roots. Landscape fabric isn't recommended under wood mulch, because the mulch breaks down on top of it and weeds root right into it.

Landscape fabric and edging

Under gravel and rock, a permeable landscape fabric keeps the stone from sinking into the soil and slows weeds. Overlap the strips by about 6 inches and pin them every 3 to 4 feet along the edges and seams. Edging along every border keeps gravel out of the lawn; the calculator counts it in 20-foot lengths.

Laying a patio instead? The paver calculator works out the base and sand layers. Pouring a slab? Use the concrete calculator.

Sources