Rock & Stone Calculator
To figure how much rock you need, multiply length × width × depth in feet and divide by 27 for cubic yards, then multiply by about 1.35–1.5 for tons of landscape rock. For example, a 20 × 10 ft bed 3 inches deep needs 1.85 cubic yards, or about 2.50–2.78 tons.
How to calculate how much rock you need
- Measure the area. Measure the length and width in feet, or use the area in square feet if you know it.
- Convert the depth to feet. Divide the depth in inches by 12. For example, 3 inches is 0.25 feet.
- Find the cubic yards. Multiply length × width × depth to get cubic feet, then divide by 27.
- Convert to tons. Multiply the cubic yards by the weight of your rock: 1.35–1.50 tons per cubic yard for landscape or drain rock. The table below gives the other types.
- Allow for compaction and round up. For base rock you'll compact, order 25–30% more. Then round up to what your supplier sells.
Worked example: a 24 × 6 ft area 4 inches deep: 24 × 6 × (4 ÷ 12) = 48 cubic feet, and 48 ÷ 27 = 1.78 cubic yards. At 1.35–1.50 tons per cubic yard, that's 2.40–2.67 tons of landscape rock.
How many tons are in a yard of rock?
It depends on the rock. Clean landscape rock and base rock weigh about the same per yard, large rock a little less, and porous lava rock about half as much.
| Rock type | Tons per yd³ | Lb per yd³ | Yd³ per ton |
|---|---|---|---|
| Landscape, decorative or drain rock | 1.35–1.50 | 2,700–3,000 | 0.67–0.74 |
| Base rock, loose | 1.43–1.48 | 2,850–2,950 | 0.68–0.70 |
| Large rock & cobblestone | 1.31–1.40 | 2,610–2,800 | 0.71–0.77 |
| Lava rock | 0.54–0.79 | 1,072–1,585 | 1.26–1.87 |
How much does a ton of rock cover?
One cubic yard covers 324 sq ft divided by the depth in inches. A ton of landscape rock is 0.67–0.74 cubic yards, and a ton of lava rock 1.26–1.87.
| Depth | Landscape rock | Lava rock |
|---|---|---|
| 1 in | 216–240 sq ft | 409–605 sq ft |
| 2 in | 108–120 sq ft | 204–302 sq ft |
| 3 in | 72–80 sq ft | 136–202 sq ft |
| 4 in | 54–60 sq ft | 102–151 sq ft |
Rock quick reference: 1 to 10 tons
| Tons | Cubic yards | Covers at 2 in | Covers at 3 in |
|---|---|---|---|
| 1 | 0.67–0.74 | 108–120 sq ft | 72–80 sq ft |
| 2 | 1.33–1.48 | 216–240 sq ft | 144–160 sq ft |
| 3 | 2.00–2.22 | 324–360 sq ft | 216–240 sq ft |
| 4 | 2.67–2.96 | 432–480 sq ft | 288–320 sq ft |
| 5 | 3.33–3.70 | 540–600 sq ft | 360–400 sq ft |
| 10 | 6.67–7.41 | 1,080–1,200 sq ft | 720–800 sq ft |
Types of rock
Landscape, decorative and drain rock
Clean, one-size rock from about ¾ to 3 inches, spread loose. It weighs 1.35–1.50 tons per cubic yard. Drain rock is the same kind of clean stone, left uncompacted so water can pass through, so it uses the same weight.
Base rock
Crushed rock mixed with fine particles, which packs down hard under paths, patios and driveways. Loose it weighs 1.43–1.48 tons per cubic yard; compacted, 1.85. That's why a compacted base needs 25–30% more loose rock than its volume suggests. Choose Compacted in the calculator and it does this for you.
Large rock and cobblestone
Rock from about 3 to 8 inches, usually laid one stone deep, so enter a depth close to the stone size. It weighs 1.31–1.40 tons per cubic yard.
Lava rock
Porous volcanic rock that weighs 0.54–0.79 tons per cubic yard, about half as much as other rock, so a ton covers roughly twice the area. Choose Lava rock in the calculator; for a round fire pit, use the circle shape.
Frequently asked questions
How much rock do I need?
Multiply length × width × depth in feet and divide by 27 for cubic yards, then multiply by about 1.35–1.5 for tons of landscape rock. A 12 × 12 ft area 2 inches deep needs 0.89 cubic yards, about 1.20–1.33 tons.
How do you calculate landscape rock?
Measure length and width in feet, divide the depth in inches by 12, multiply the three for cubic feet, and divide by 27 for cubic yards. For example, 24 ft × 6 ft × 4 in is 48 cubic feet, or 1.78 cubic yards.
How many tons of rock do I need?
Multiply the cubic yards by the rock's weight per yard: 1.35–1.50 tons for landscape or drain rock, 1.43–1.48 for loose base rock (1.85 compacted), 1.31–1.40 for large rock and cobblestone, and 0.54–0.79 for lava rock.
How much rock is in a yard?
A yard of rock is one cubic yard: 27 cubic feet, a cube 3 feet on each side. Landscape rock weighs about 2,700–3,000 lb per yard, and a yard covers 108 sq ft at 3 inches deep.
How much does a ton of rock cover?
A ton of landscape rock covers about 108–120 sq ft at 2 inches deep, 72–80 sq ft at 3 inches or 54–60 sq ft at 4 inches. Lava rock is lighter, so a ton covers 204–302 sq ft at 2 inches.
How much is a ton of rock?
Prices depend on the rock, your region and delivery, so ask local suppliers for a quote. Then multiply: tons × the price per ton, or cubic yards × the price per yard. Enter the price in the calculator's price field to get a total.
How much does lava rock weigh?
Loose lava rock weighs about 0.54–0.79 tons per cubic yard (1,072–1,585 lb), or 40–59 lb per cubic foot, in Texas Highway Department tests: roughly half as much as other landscape rock. A 36-inch round fire pit filled 4 inches deep holds about 2.36 cubic feet, or 94–138 lb of lava rock.
How much base rock do I need?
Work out the cubic yards of the finished base, then order 25–30% more if you'll compact it: Washington State DOT lists crushed surfacing at 1.43–1.48 tons per cubic yard loose and 1.85 compacted.
How much drain rock do I need?
Multiply length × width × depth in feet and divide by 27, then multiply by 1.35–1.50 for tons. Drain rock is clean, one-size stone that's left loose, so no compaction allowance is needed: a 50 ft trench 1 ft wide and 1 ft deep takes 1.85 cubic yards, about 2.50–2.78 tons.
How much does a ton of cobblestone cover?
Large rock and cobblestone weigh about 1.31–1.40 tons per cubic yard, so a ton covers about 58–62 sq ft laid 4 inches deep. Enter a depth close to the stone size.
Related calculators
Sources and methodology
Volumes use (length × width × depth) ÷ 27 with all measurements in feet. Weights are loose, as delivered: landscape and drain rock run from the Federal Highway Administration's figure for dry, uniformly graded gravel to Penn State's figure for AASHTO #57 stone; large rock from FHWA's riprap rock to Penn State's R-3 to R-6 riprap; base rock uses Washington State DOT's crushed surfacing; and lava rock uses the Texas Highway Department's loose unit weights for volcanic scoria. That's why results show a range. For compacted base rock, the calculator works out the weight needed to fill the compacted volume, then converts it to the loose cubic yards you order. Tons are US short tons (2,000 lb). Order amounts are rounded up to the next half cubic yard or half ton.
- FHWA Federal Lands Highway, Earthwork Design (PDDM supplement), Exhibit 5.1 A (January 2026)
- Penn State Center for Dirt and Gravel Road Studies: DGLVR Materials Calculator
- WSDOT Design Manual M 22-01.23, Exhibit 620-1 (September 2024)
- Texas Highway Department, Materials and Tests Division: Scoria, a Natural Lightweight Aggregate (T. S. Patty, 1971)
- NIST Special Publication 811 (Guide for the Use of the SI), Appendix B.8: conversion factors