Gravel Calculator

Why Gravel Quantity Matters for Your Project

Gravel is one of the easiest materials to underorder, and this free gravel calculator helps you get the number right the first time by handling both units suppliers use. A walkway needs only 2 inches of decorative pea gravel; a driveway base needs 4 to 6 inches of compacted crushed stone; a drainage trench needs 6 to 8 inches of clean stone. Order the wrong depth and you either have a thin layer that ruts immediately or a pile of leftover material you've paid to deliver twice.

The bigger complication is that gravel is sold in two different units — volume (cubic yards) and weight (tons) — and suppliers use whichever one favors their pricing model. A ton of pea gravel is not the same volume as a ton of crushed stone, because different gravels have different densities. Knowing your project's requirements in both tons and cubic yards lets you compare quotes accurately and catch ordering errors before the truck arrives. If the project also includes a fence line, the fence post concrete calculator handles post count and concrete bags alongside your gravel estimate.

How to Use This Calculator

1. Enter your area. Switch between Length × Width and Area tabs. For irregular shapes like curved driveways, break the area into rectangles and add the results.
2. Set depth and choose gravel type. Slide to your target depth and select the gravel type — this updates the ton estimate to match the density of what you're buying. Enable the compaction toggle for driveways, base layers, or any project run over with a plate compactor.
3. Enter pricing to see cost. Type in the price per ton from your local supplier's quote. The results card shows cubic yards, tons, bag count, and total estimated cost side by side.

How to Calculate Gravel Manually

1. Measure your project area in square feet (length × width for rectangles).
2. Determine target depth in inches: 2–3" for decorative beds and walkways, 4–6" for driveway bases, 6–8" for drainage applications.
3. Calculate cubic feet: area × (depth ÷ 12). Example: 400 sq ft at 4 inches → 400 × 0.333 = 133 cubic feet.
4. Convert to cubic yards: divide cubic feet by 27. (133 ÷ 27 = 4.9 cu yd.)
5. Convert to tons: multiply cubic yards by the gravel's density factor — 1.4 for pea gravel, 1.5 for crushed stone, 1.35 for river rock, 1.6 for decomposed granite.
6. Add 10% for waste and compaction: multiply your final ton or yard figure by 1.10 and round up.

Gravel Types — Weight and Coverage Comparison

Densities are approximate and vary by supplier. Verify the cost range with a local quote before ordering. If you're building a retaining wall, backfill gravel is estimated separately in the retaining wall block calculator.

Common Gravel Estimation Mistakes

Forgetting that gravel compacts. Loose gravel settles 15–20% under foot traffic or plate compaction. If you want 4 inches of finished driveway surface, order for 4.8 to 5 inches loose. Skipping this is the single most common reason projects end up short — the compaction toggle in the calculator handles this automatically.

Confusing tons and cubic yards. Suppliers sometimes quote by ton, sometimes by yard, and the two are not interchangeable — they depend on the gravel's density. Always get both numbers from your supplier or use the calculator to convert, then verify that the ton count divided by your gravel's density matches the cubic yard count before you confirm the order.

Not separating the sub-base from the surface layer. A proper driveway has two distinct layers: a compacted base of angular crushed stone (4–6 inches) and a finer surface layer (2–3 inches). Calculate and order each separately — different materials, different depths, sometimes different suppliers.

Ordering river rock by volume when it's priced by weight. River rock is denser than its rounded shape suggests. A small volume of large river rock can weigh significantly more than expected — always confirm the ton price and convert to cubic yards using the 1.35 density factor before you commit to a quantity.

Frequently Asked Questions

How many tons of gravel do I need for a driveway?

A standard 12×30-foot driveway (360 sq ft) with a 4-inch compacted crushed-stone base needs roughly 10 tons before compaction allowance — about 11 tons with the 10% buffer. Add a 2-inch surface layer and total material rises to approximately 15 tons. Use the calculator above with your actual dimensions for a precise order quantity. If the driveway includes a gate or fence posts, the fence post concrete calculator prices the footings alongside your gravel order.

What is the difference between cubic yards and tons?

Cubic yards measure volume; tons measure weight. One cubic yard of pea gravel weighs about 1.4 tons; the same volume of crushed stone weighs about 1.5 tons. Your supplier may quote in either unit — always confirm which one before calculating your order, and use the density factor to convert between the two.

How deep should gravel be for a patio base?

A compacted gravel base under pavers or flagstone should be 4 inches thick after compaction — order for 5 inches loose to account for the 15–20% that compacts away. For a simple loose gravel patio with no pavers, 3–4 inches of finished depth provides adequate coverage and drainage.

Does gravel need to be compacted?

Yes, for driveways, base layers under pavers, and drainage applications. Compact in 2- to 3-inch lifts with a plate compactor for best results. Decorative top-dressing over landscape fabric does not need mechanical compaction. Skipping compaction on load-bearing gravel causes rutting, shifting, and rapid deterioration. For decorative beds alongside your gravel project, the mulch calculator covers cubic yards and bag counts at any depth.

How much does a ton of gravel cover?

One ton of crushed stone (1.5 tons/cu yd) covers roughly 100 square feet at 2 inches deep, or about 50 square feet at 4 inches. Pea gravel (1.4 tons/cu yd) covers slightly more per ton at the same depth. Enter your gravel type and depth in the calculator above for the exact coverage your project requires.