Gravel Calculator — How Much Gravel Do I Need?
Enter your project dimensions below and get cubic yards, tons and bag counts instantly — free, no sign-up, nothing to install.
Quick start
- Pick a shape: rectangle, circle or border.
- Type dimensions and depth — results update as you type.
- Choose your material to convert yards to tons.
- Bookmark or print the summary for your supplier.
Gravel calculator
Density shown is an industry-typical value and varies by supplier — confirm before ordering.
You need
Includes +10% extra
36.0
cubic feet
1.33
cubic yards
1.87
tons (2,000 lb)
72
bags (0.5 cu ft)
≈ 0.76 m³
Estimated cost: $0.00 (at $0/ton)
Order 5–10% extra for compaction and settling — loose gravel always settles to less volume after compaction.
How much gravel do you need? Multiply length × width × depth in feet and divide by 27 to get cubic yards, then multiply by about 1.4–1.6 to convert yards to tons. A 12 ft × 12 ft area at 3 inches deep is 36 cubic feet — 1.33 cubic yards, or about 1.9 tons of #57 crushed stone. Use the calculator above for your exact dimensions, material and waste allowance.
How the gravel math works
The calculator converts your dimensions to feet, computes the volume in cubic feet, then divides by 27 (the number of cubic feet in a cubic yard). Weight in tons comes from multiplying that volume by the material's typical density. Every formula below is plain arithmetic you can check by hand.
Rectangle or square
cu yd = L(ft) × W(ft) × D(ft) ÷ 27
Length times width gives the footprint in square feet; multiplying by depth (in feet — so 3 inches = 0.25 ft) gives cubic feet.
Circle
cu yd = π × radius(ft)² × D(ft) ÷ 27
The radius is half the diameter and π ≈ 3.1416. A 10-foot-diameter fire-pit circle at 3 inches deep holds about 0.73 cubic yards.
Border or path (a ring of gravel)
cu yd = (outer area − inner area) × D(ft) ÷ 27
The inner area is the outer rectangle shrunk by twice the border width on each side — the calculator subtracts it for you, the same math used for tree rings and bed edging.
Converting cubic yards to tons
tons = cu yd × density (tons per cu yd)
Typical densities: pea gravel and #57 crushed stone ≈ 1.4, #411 ≈ 1.5, crusher run ≈ 1.6, river rock ≈ 1.35, lava rock ≈ 0.7 tons per cubic yard. These are industry-typical values — see our density methodology and confirm with your supplier.
Converting to bags
bags = cubic feet ÷ 0.5
Bagged gravel is commonly sold in 0.5-cubic-foot bags (a typical 50 lb bag of #57 stone). One cubic yard equals 54 such bags.
Worked example: 12 × 12 patio at 3 inches
A 12 ft × 12 ft patio at 3 inches deep needs 1.33 cubic yards of gravel — about 1.9 tons of #57 crushed stone, or 72 half-cubic-foot bags. Here is every step of the math, exactly as the calculator runs it.
- Footprint: 12 ft × 12 ft = 144 sq ft
- Depth in feet: 3 in ÷ 12 = 0.25 ft
- Volume: 144 × 0.25 = 36 cubic feet
- Cubic yards: 36 ÷ 27 = 1.33 cu yd
- Tons of #57 (density 1.4): 1.33 × 1.4 = 1.87 tons ≈ 1.9 tons
- Bags: 36 ÷ 0.5 = 72 bags
- With the recommended 10% extra for compaction: about 1.47 cu yd ≈ 2.05 tons
Try it: the calculator above starts pre-filled with exactly these numbers. Change anything and the results update instantly.
How deep should gravel be?
Match depth to the job: 2–3 inches for pathways and decorative areas, 4 inches for a driveway surface, and pipe-sized depths for French drains. Deeper is not better — loose gravel over 4–6 inches shifts under load unless it is compacted in layers.
| Project | Typical depth | Notes |
|---|---|---|
| Walkway / path | 2–3″ | Over 2–3″ compacted base; edge it to stop spread |
| Driveway surface | 4″ | Over sub-base; crusher run or #411 compacts best |
| New driveway (full build-up) | 8–12″ total | Larger sub-base stone under the 4″ surface |
| French drain | varies | 2″ under pipe, 2–3″ above; trench usually 18–24″ deep |
| Shed pad | 4–6″ | Compacted crusher run, 1–2 ft larger than the shed |
| Decorative bed topping | 2″ | Over landscape fabric |
Project pages have full build-up guidance: driveways, patios, French drains, walkways and shed pads.
Which material should you calculate for?
Pick the material before you order, because densities — and therefore tonnage — differ by up to a factor of two. Lava rock runs about 0.7 tons per cubic yard while crusher run hits 1.6, so the same volume is less than half the weight.
- Crushed stone #57 — all-purpose drainage, bases, driveways (≈1.4 t/yd³)
- Crusher run — compactable driveway and pad base (≈1.6 t/yd³)
- Pea gravel — comfortable paths and play areas (≈1.4 t/yd³)
- River rock — decorative beds and dry creeks (≈1.35 t/yd³)
- Decomposed granite — firm paths and patios (≈1.4 t/yd³)
- Lava rock — lightweight decorative cover (≈0.7 t/yd³)
Not sure how grades like #57 and #411 differ? See the gravel size chart.
Frequently asked questions
How much gravel do I need for my project?
Multiply length × width × depth in feet to get cubic feet, then divide by 27 for cubic yards. A 12 ft × 12 ft patio at 3 inches deep needs about 1.33 cubic yards, or roughly 1.9 tons of #57 crushed stone. The calculator above does this instantly for any shape.
How do I convert cubic yards to tons?
Multiply cubic yards by the material’s density in tons per cubic yard. Most crushed stone averages 1.4–1.5 tons per yard, crusher run runs about 1.6, and lightweight lava rock is near 0.7. Densities are typical values — confirm your supplier’s actual weight.
How many bags of gravel equal a cubic yard?
One cubic yard is 27 cubic feet, so it takes 54 bags of 0.5 cubic feet each. Bagged gravel typically costs far more per cubic yard than bulk delivery, so bags only make sense for small patch jobs.
How deep should gravel be?
Use 2–3 inches for decorative pathways, 4 inches for a driveway surface over a compacted base, and a depth sized to your pipe for French drains. Anything deeper than 4–6 inches in one lift should be compacted in layers.
Why should I order extra gravel?
Order 5–10% extra for compaction and settling. Gravel compacted with a plate compactor can lose 10% or more of its loose volume, and edges always need a little extra. The calculator has a toggle that adds the allowance for you.
Is this gravel calculator free?
Yes — GravelCalc Pro is completely free, requires no sign-up, and runs entirely in your browser. Your inputs are saved only on your device, and you can bookmark or share the exact calculation using the link button.