Estimate gravel volume in cubic yards and tons for driveways, walkways, drainage, and patio base. Six material densities, four shapes, compaction allowance, bags and truckloads.
| Format | Each | Quantity |
|---|---|---|
| 50-lb bag | 50 lb | 457 |
| 1-ton big bag | 2,000 lb | 12 |
| Small dump truck | 6 yd³ | 2 |
| Standard dump truck | 12 yd³ | 1 |
Advanced · density override · price · custom truck
Reverse: I have a fixed tonnage
Enter how many tons you have on hand and your target depth — see the area you can cover at the current material density.
How the math works
Gravel is sold by weight (tons) but spread by volume (cubic yards). Four steps:
- Area by shape: rectangle (L × W), circle (π × r²), triangle (½ × base × height), or trench (length × width).
- Loose volume:
area × depth_in / 12 ÷ 27= cubic yards. - Loose tons:
yards × density(density depends on rock type — table below). - Order with compaction:
loose tons × (1 + compaction%). A driveway base settles 10–20% under traffic — order more so finished depth matches the plan.
Density table — six common gravels
| Material | Density (t/yd³) | Typical use |
|---|---|---|
| Pea gravel (3/8″ rounded) | 1.30 | Garden paths, playgrounds, mulch |
| 3/4″ crushed stone (#57) | 1.40 | Driveway base, French drains, paver sub-base |
| Crushed limestone | 1.50 | Driveway surface, agricultural lime |
| River rock (rounded, washed) | 1.50 | Decorative beds, dry creek beds, drainage swales |
| DGA / quarry process | 1.50 | Compacted base for pavers, walkways, sheds |
| Lava rock (pumice) | 0.70 | Lightweight ground cover, fire pits, planters |
Loose-pour values from typical aggregate suppliers (Vulcan, Martin Marietta, Lehigh Hanson). Wet or fines-heavy material runs 5–10% heavier — paste your slip’s number into the density override in Advanced.
Depth recommendations
- 2–3″ — walkways, garden paths, decorative beds
- Pea gravel or river rock. Goes over a weed barrier if you want to keep edges clean.
- 4–6″ — residential driveways, patio bases, shed pads
- 3/4″ crushed stone (#57) or DGA. 4″ for cars only, 6″ if a heavy truck or RV will sit on it.
- 6″+ — French drains, drainage swales, sub-base under pavement
- 3/4″–1.5″ angular crushed (drainage gravel) wrapped in geotextile so fines don’t migrate up and clog the void space.
Worked example — 20 × 30 ft driveway at 4″ of #57 crushed
- Area:
20 × 30 = 600 ft² - Loose volume:
600 × (4 / 12) ÷ 27 = 7.41 yd³ - Loose tons:
7.41 × 1.40 = 10.37 t - Order with 10% compaction:
10.37 × 1.10 = 11.41 t(≈ 8.15 yd³) - Format options: 12 × 1-ton big bags, or one standard dump truck (12 yd³), or two small dump trucks (6 yd³ each)
Bagging this driveway in 50-lb retail bags would mean ceil(11.41 × 2000 ÷ 50) = 457 bags — about 11 pallets. Bag math is the wrong tool above ~1 ton; bulk delivery is roughly 1/4 of the per-ton retail price.
Common questions
Why add a compaction allowance?
What you order is loose-poured material — particles surrounded by air voids. Once it’s walked on, rolled with a plate, or settled by a freeze-thaw cycle, it compacts 10–20%. Order the loose volume that gives the finished depth you want: 10% for residential foot or car traffic, 15–20% for a vibratory plate or road sub-base, and 0% for a decorative top layer over an already-stable surface.
Do I need a weed barrier or geotextile under it?
Different fabrics, different jobs. Landscape weed fabric under pea gravel or river rock holds back surface weeds for 3–5 years; nothing structural. Geotextile separator (4–8 oz/yd²) under a French drain or driveway sub-base stops soil fines from migrating up into the void space — without it, a #57 drain field clogs in 2–3 wet seasons.
What edging keeps a gravel driveway from spreading?
Without edging, gravel migrates outward 1–2 inches a year from tyre push and rain. Three that hold up: steel landscape edging (3/16″, anchored every 30″) is the cleanest and survives plough strikes; pressure-treated 4×4 timbers at 24″ intervals are cheaper but need replacing at 8–10 years; Belgian block on a 6″ #57 base is the most permanent.
For driveway base specs and aggregate gradations beyond #57, see the crushed stone calculator. For the bedding sand layer under pavers, see the sand calculator. Estimator only — densities vary by quarry, season, and moisture; use this to size the order, not as engineering acceptance for retaining walls or load-bearing fills.
