Landscape Rock Calculator

How to calculate how much landscape rock you need

Landscape rock is sold by volume (cubic yards) and by weight (tons). Work out the volume of each bed first, then turn it into weight with the density of your rock.

Use one area for each bed and the totals add up as you type. Measurements like 10'6" or 10 ft 6 in work too. The extra box adds the allowance your supplier recommends to the volume and the weight together.

Example: three beds with river rock

A yard has a 20 ft by 15 ft rectangular bed at 3 inches, a triangular bed with a 12 ft base and an 8 ft height at 3 inches and a round bed 10 ft across at 4 inches. The rock is river rock at 2,950 pounds per cubic yard, the midpoint of the 2,700 to 3,200 range below, with 10% extra and 40 lb bags.

The three beds add up to 426.5 square feet, so one ton covers about 69 square feet at their average depth of 3.2 inches. Across the whole 2,700 to 3,200 range the order is 6.22 to 7.38 tons.

How much does a cubic yard of landscape rock weigh?

The first column of figures is from GoodGravel, an information site on gravel and rock types, and the cross-check is the weight list of Stone Centers, a stone supplier in Ohio. Both were checked in October 2026. Tons are the pounds divided by 2,000.

These are ranges, not exact values, and the two sources do not always agree. Lava rock is the clearest case, because the lists do not overlap at all. Stone Centers also warns that its weights are approximate and move with moisture and compaction. If your supplier gives a figure for the product you are buying, choose “Custom density” and type it.

How many square feet does one ton of rock cover?

A ton is 2,000 pounds, so the area it covers is the volume of a ton divided by the depth. The first table uses the midpoint of each GoodGravel range, rounded to the nearest square foot. Lighter rock stretches further.

Coverage by rock size

Big rock is sold by the ton and does not lay flat like pebbles, so suppliers quote coverage by size. Bedrock Landscaping Materials, a supplier in Colorado, publishes the guideline below, which it calls approximate. Checked October 2026.

The same page says one ton of rock covers 240 square feet at 1 inch, 120 at 2, 80 at 3, 60 at 4, 50 at 5 and 40 at 6. Those figures match a weight of about 2,700 pounds per cubic yard, which sits inside the ranges above. The calculator uses the weight of the material and not the size of the stones, so for boulders and wall stone trust the per ton coverage from your supplier.

How deep should landscape rock be?

Stone Centers recommends a minimum of 2 inches for decorative pea gravel and river rock, including dry creek beds. For drainage behind a retaining wall it suggests washed gravel at least 12 inches deep from the wall, and under pavers it points to 4 to 6 inches of crushed limestone or paver base. These are one supplier’s guidelines and not a code, so adjust them to your soil, your slope and your contractor’s advice.

Tips for ordering

• Ask how the supplier sells the rock. Many price by the ton, so the tons in the result are the number to compare.
• Ask for the weight of the exact product and type it as a custom density.
• For an odd shape, split it into rectangles, circles and triangles and add each as an area.
• For gravel used as a base or fill, see the gravel calculator. For beds of bark, see the mulch calculator.
• For one material in more depth, see the river rock and pea gravel calculators.
• To convert a weight into volume and back, use the tons to cubic yards converter.

Frequently asked questions