Gravel Calculator

A 20 ft by 10 ft area covered with gravel 3 inches deep needs about 1.85 cubic yards — roughly 2.6 tons of standard gravel, or close to 104 bags of 50 lb. That single line is the whole job of this gravel calculator: turn a length, a width, and a depth into the cubic yards, tons, and bags you actually have to order. Buy a little extra (about 10%), and you will not be stuck spreading a patchy layer or paying for a second delivery.

The formula

Every gravel estimate comes down to volume, then a conversion to weight. The volume math is:

Length and width are in feet, depth is in inches (so divide by 12 to convert to feet), and dividing the resulting cubic feet by 27 gives cubic yards — because a cubic yard is 3 ft × 3 ft × 3 ft = 27 cubic feet. To get weight, multiply the cubic yards by the gravel's density:

Standard gravel runs about 2,800 lb per cubic yard (≈ 1.4 tons). The calculator does both steps for you and lets you switch the gravel type if you are using pea gravel, crushed stone, or crusher run.

Worked example with real numbers

Suppose you are graveling a small parking pad that measures 24 ft long by 12 ft wide, and you want it 4 inches deep. First the area: 24 × 12 = 288 square feet. Convert depth to feet: 4 ÷ 12 = 0.333 ft. Volume: 288 × 0.333 = 96 cubic feet, which is 96 ÷ 27 = 3.56 cubic yards. Using standard gravel at 2,800 lb per yard, that is 3.56 × 2,800 = 9,955 lb, or about 4.98 tons. Add the recommended 10% overage and you would order roughly 3.9 cubic yards (about 5.5 tons). That overage covers the gravel that disappears into the sub-grade and compacts down as you tamp it.

How to measure your area

Accurate inputs matter more than the math. A few minutes with a tape measure saves a wasted delivery:

1. Length and width: measure in feet at the widest points. For a rough or curved shape, break it into rectangles, calculate each, and add them up.
2. Irregular shapes: for a circle, area is π × radius² ; for a triangle, ½ × base × height. Convert any shape to square feet with the Square Footage Calculator, then treat it like a rectangle for depth.
3. Depth: decide the finished thickness in inches. Walkways need less, driveways need more (see below). Measure depth as the compacted layer you want, then add overage for settling.
4. Slopes and dips: if the ground is uneven, use the average depth needed to bring it level — low spots eat more gravel than you expect.

How to use this calculator

Enter your numbers and read the result at the top:

1. Length and width (feet): the footprint of the area you are covering.
2. Depth (inches): the finished gravel thickness — tap one of the 2", 3", 4", or 6" presets or type your own.
3. Gravel type: pick the closest match so the tonnage uses a realistic density. Override with your supplier's figure if you have it.
4. Calculate: the headline shows cubic yards; the cards below show cubic feet, tons, 50 lb bags, and the amount to order with 10% extra.

The depth-coverage table then shows how the same area would change at other depths, so you can see the trade-off before you commit.

What depth do you need?

Depth is the input people most often get wrong, and it scales the order directly — doubling the depth doubles the gravel. Typical guidance:

• Decorative beds & ground cover: about 2 inches over landscape fabric.
• Walkways & garden paths: 2–3 inches, often over a thin base.
• Patios & light foot traffic: 3 inches of finished stone.
• Driveways: 4 inches or more for the top layer, usually over a compacted base course; heavy-use or soft-soil driveways are built deeper in multiple lifts.

Who this calculator is for

Anyone who needs to turn a project area into an order is in the right place:

• Homeowners graveling a driveway, path, patio, or fire-pit area.
• Landscapers and gardeners filling beds, French drains, or dry creek beds.
• DIY builders laying a sub-base under pavers, sheds, or concrete.
• Anyone comparing prices who needs cubic yards and tons to quote a delivery accurately.

Key terms explained

• Cubic yard (yd³): a cube 3 feet on each side = 27 cubic feet. The standard unit for bulk gravel.
• Density: the weight of gravel per unit of volume (lb per cubic yard). It converts volume to tons and varies by stone type and moisture.
• Coverage: how much area a given amount covers at a stated depth — one ton of standard gravel covers about 100 sq ft at 2 inches.
• Waste / overage factor: the extra you order (about 10%) to absorb compaction, spillage, and uneven ground.
• Crusher run: a dense mix of crushed stone and fines that compacts hard — heavier per yard and good for bases.
• Pea gravel: small, rounded stones that are lighter per yard and prone to scattering, so edging helps.

Three common scenarios

• Garden path, 40 ft × 3 ft at 2": 120 sq ft × 0.167 ft = 20 cubic feet = about 0.74 cubic yards (≈ 1.0 ton). A small job that bagged gravel could handle (~42 bags of 50 lb).
• Patio, 16 ft × 16 ft at 3": 256 sq ft × 0.25 ft = 64 cubic feet = about 2.37 cubic yards (≈ 3.3 tons). Bulk delivery makes sense at this size.
• Driveway, 50 ft × 12 ft at 4": 600 sq ft × 0.333 ft = 200 cubic feet = about 7.4 cubic yards (≈ 10.4 tons). Order in tons and plan for a base layer beneath.

Factors that change the result

If you adjust the inputs and watch the numbers move, a few factors clearly dominate:

• Depth: the most sensitive input — it multiplies the volume directly, so a 2" vs 4" decision doubles your order.
• Area: length and width together set the footprint; an error here scales everything.
• Density / gravel type: only affects the weight (tons), not the volume. It matters when you buy by the ton.
• Compaction: gravel settles when tamped, so the in-place depth is less than the loose depth — another reason for overage.
• Sub-grade: soft or uneven ground soaks up extra gravel before you reach the finished surface.

Practical tips

• Always order about 10% extra. Running short means a second delivery charge that dwarfs the cost of a little surplus.
• Buy bulk over bags for anything more than a cubic yard or two — it is far cheaper per ton.
• Lay landscape fabric under decorative gravel to slow weeds and keep stones from sinking into soil.
• Compact in layers (lifts) for driveways rather than one deep pour, so the base sets up firmly.
• Confirm density with your supplier if you are ordering by weight; stated tonnage can swing 10% with stone type and moisture.

Limitations and assumptions

This is a planning estimate, not a supplier quote. A few things to keep in mind:

• It assumes a uniform, level area at a single depth; irregular ground and slopes need averaging.
• Density is an approximation; real loads vary with stone size, type, and moisture, so tonnage can differ by 10% or more.
• It does not size a separate base or sub-base course — driveways and patios usually need one beneath the decorative layer.
• The 10% overage covers normal spillage and compaction, but very soft sub-grade may need more.
• Delivery fees, edging, and labor are not included.

Gravel types and how their density differs

The volume your project needs never changes, but the weight you pay for does, because each gravel type has a different density. Picking the right type in the calculator keeps the tonnage realistic:

• Pea gravel (≈ 1.3 tons/yd³): small, smooth, rounded stones that drain well and feel soft underfoot. Lightest common type, great for paths and play areas, but it scatters without edging.
• Standard / washed gravel (≈ 1.4 tons/yd³): the all-purpose default the calculator uses unless you change it. A safe estimate for most decorative and drainage jobs.
• Crushed stone (≈ 1.5 tons/yd³): angular fragments that lock together and stay put on slopes. Slightly heavier per yard than rounded gravel.
• Crusher run / road base (≈ 1.5–1.6 tons/yd³): a dense mix of crushed stone and stone dust (fines) that compacts into a near-solid surface — the heaviest and best choice for driveway and patio bases.

Because density only affects the tons figure, two suppliers can quote the same cubic yards but different tonnage. If you buy by weight, always match the type or enter the supplier's exact density. For non-stone landscape fill, the same idea applies — bark and wood chips are far lighter, which is why the Mulch Calculator uses a different density entirely.

Estimating cost: bulk vs. bagged gravel

Once you know the cubic yards and tons, cost follows quickly. Bulk gravel is usually priced per ton or per cubic yard delivered, while bagged gravel is priced per bag. The crossover point is small: above roughly one to two cubic yards, bulk delivery is dramatically cheaper per pound than bags, even after the delivery fee. To turn the calculator's tonnage into a budget, multiply your tons (including the 10% overage) by your supplier's price per ton, then add the flat delivery charge. For a quick gut-check, the worked driveway example above (about 7.4 cubic yards, ≈ 10.4 tons) would take more than 400 fifty-pound bags — clearly a job for bulk delivery rather than the hardware-store aisle. Use the headline cubic-yard figure when a supplier sells by volume and the tons figure when they sell by weight; ordering in the unit your supplier quotes avoids rounding surprises.

Building it in layers: base, sub-base, and top

For anything that bears weight — a driveway, a patio, a shed pad — gravel is rarely a single layer. A typical build is a compacted sub-base of crusher run over the prepared sub-grade, then a finer top course of decorative gravel. Each layer has its own depth, so calculate them separately and add the results: run the calculator once at the base depth (often 4–6 inches of crusher run) and again at the top-course depth (1–2 inches of decorative stone). Compacting in shallow lifts — spreading and tamping a few inches at a time rather than dumping the whole load — produces a far firmer, longer-lasting surface than one deep pour. If you are pouring concrete over the base instead of leaving gravel exposed, switch to the Concrete Calculator for that layer, and size the footprint first with the Square Footage Calculator.

Related materials and calculators

The same volume math applies to most landscape materials, so a sister tool may fit better:

• Pouring a slab or footing? Use the Concrete Calculator for cubic yards of concrete.
• Filling beds with bark or wood chips? The Mulch Calculator handles cubic yards and bags.
• Spreading sand for a base or paver-setting bed? The Sand Calculator converts the same dimensions to tons.
• Need volume for any material? The Cubic Yard Calculator converts dimensions for sand, soil, or stone.
• Just sizing an area? The Square Footage Calculator gets you the footprint first.

Sources

• National Institute of Standards and Technology (NIST) — unit conversion (cubic feet to cubic yards, the 27 ft³ = 1 yd³ relationship).
• U.S. Geological Survey (USGS) — Construction sand and gravel statistics and information.
• Densities are typical published ranges for landscape gravel and vary with stone type, gradation, and moisture — confirm the exact figure with your supplier when ordering by the ton.