How to Calculate Cubic Yards
Cubic yards measure volume — the amount of three-dimensional space something occupies. It's the standard unit used by US suppliers to sell bulk materials like concrete, gravel, topsoil, mulch, and sand. Calculating cubic yards isn't complicated, but it trips people up because depth is usually in inches while length and width are in feet, so you have to convert units along the way.
(all dimensions in feet)
OR
Cubic Yards = (Length × Width × Depth in inches) ÷ 324
(length and width in feet, depth in inches)
The number 27 comes from the fact that 1 cubic yard equals 27 cubic feet — picture a 3-foot cube: 3 × 3 × 3 = 27. The number 324 is just 27 × 12, combining the unit conversion and the cubic-foot-to-cubic-yard conversion into one step.
Worked example
Suppose you're filling a planter bed 20 feet long × 10 feet wide × 4 inches deep with topsoil:
- Volume in cubic feet: 20 × 10 × (4 ÷ 12) = 66.67 ft³
- Volume in cubic yards: 66.67 ÷ 27 = 2.47 yd³
- Weight (topsoil at 1.3 t/yd³): 2.47 × 1.3 = 3.21 tons
When You Need to Calculate Cubic Yards
Almost any bulk material sold in volume rather than weight uses cubic yards as the standard unit in the US. Here are the most common scenarios where this calculator is useful.
Concrete
Concrete is sold and priced exclusively by the cubic yard in the US (ready-mix delivery) and Canada (often in cubic meters too). A typical residential slab — say a 10 × 12 ft patio at 4 inches thick — needs 1.48 cubic yards. A truck holds 8–10 yards, so smaller jobs pay a "short load" surcharge of $50–150 per delivery.
Topsoil and garden beds
Filling raised beds, leveling lawns, or installing new garden areas. A 100 sq ft raised bed at 12 inches deep takes 3.7 cubic yards. For a full lawn install at 4 inches of topsoil over 500 sq ft, you'd order 6.2 yards (about 8 tons).
Mulch
Mulch is the lightest common bulk material — about 0.95 tons per cubic yard. A typical ornamental bed gets 2–4 inches of mulch annually. A 300 sq ft bed at 3 inches needs 2.78 cubic yards. For comparison, a standard bagged mulch (2 cu ft) takes 13.5 bags to equal 1 cubic yard.
Gravel and crushed stone
Driveways, French drains, pathways, and decorative landscape gravel. A standard 20 × 10 ft driveway at 6 inches deep needs 3.7 cubic yards (around 5 tons). Always pad your gravel estimate by 5–10% to account for compaction and edge spillage.
Sand
Paver base, playground surfaces, masonry work, sandboxes. A typical paver patio sub-base is 1 inch of sand: a 200 sq ft patio needs 0.62 cubic yards of bedding sand, plus extra for joint filling.
Asphalt and pavement
Repaving driveways or laying new asphalt. Hot mix asphalt weighs about 2.03 tons per cubic yard. A 600 sq ft driveway at 3 inches of asphalt needs 5.55 cubic yards (≈ 11 tons). Always order via a paving contractor — hot-mix delivery has tight timing requirements.
Compost, manure, and amendments
Soil amendments and garden compost are typically delivered by the yard. Compost runs about 1.1 tons per cubic yard. For a typical vegetable garden refresh, plan on 1–2 inches of compost worked into existing soil.
How Big Is a Cubic Yard? Real-World Visualization
One cubic yard is a cube measuring 3 feet (or 36 inches) on every side. To put that in perspective, here are some comparisons:
- 27 cubic feet — the same volume as 27 boxes that are 1 ft × 1 ft × 1 ft
- ~202 US gallons — equivalent to 4 standard 55-gallon drums
- ~765 liters — for metric reference
- 0.76 cubic meters — slightly less than 1 m³
- Visually: roughly the size of a standard washing machine on its side, or a small refrigerator turned over
- In a pickup truck: a standard half-ton truck bed holds approximately 1.5–2 cubic yards of mulch (or 1 cubic yard of dirt due to weight limits)
Cubic Yards by Material Weight
Different materials weigh very different amounts per cubic yard. This matters because most suppliers will quote price per yard but charge by weight, and trucks have legal weight limits that may cap your load size before volume does.
| Material | Weight per yd³ | Typical use |
|---|---|---|
| Mulch (wood chips) | 0.95 tons (1,900 lb) | Garden beds |
| Compost | 1.10 tons (2,200 lb) | Soil amendment |
| Topsoil (dry) | 1.30 tons (2,600 lb) | Lawns, beds |
| Gravel (standard) | 1.35 tons (2,700 lb) | Driveways |
| Sand (dry) | 1.35 tons (2,700 lb) | Paver base |
| Crushed stone | 1.42 tons (2,840 lb) | Driveway base |
| Dirt / fill | 1.45 tons (2,900 lb) | Grading, fill |
| Pea gravel | 1.50 tons (3,000 lb) | Walkways, patios |
| Wet sand | 1.60 tons (3,200 lb) | Same uses, post-rain |
| Asphalt (hot mix) | 2.03 tons (4,060 lb) | Paving |
| Concrete (mixed) | 2.40 tons (4,800 lb) | Slabs, footings |
Note that wet materials weigh significantly more — wet topsoil can hit 1.7 tons/yd³, and saturated dirt approaches 2 tons. If you're ordering after rainy weather, factor this in when checking truck capacity.
Cubic Yard, Cubic Foot, Cubic Meter — Conversions
Three different cubic units appear constantly in construction and landscaping. Here's how they relate:
| From | To Cubic Yards | To Cubic Feet | To Cubic Meters |
|---|---|---|---|
| 1 Cubic Yard | 1.00 | 27.00 | 0.7646 |
| 1 Cubic Foot | 0.037 | 1.00 | 0.0283 |
| 1 Cubic Meter | 1.308 | 35.31 | 1.00 |
| 1 US Gallon | 0.00495 | 0.1337 | 0.00379 |
| 1 Liter | 0.00131 | 0.0353 | 0.001 |
Common shortcuts: cubic feet to cubic yards, divide by 27. Cubic yards to cubic meters, multiply by 0.765. Cubic meters to cubic yards, multiply by 1.308. Most US suppliers stick with cubic yards exclusively; international or Canadian suppliers sometimes switch between yards and meters depending on the material.
How Many Cubic Yards in a Dump Truck
Knowing truck capacity is essential when ordering delivery — both for what you order and for what's actually feasible on your property.
- Pickup truck (1/2 ton): 1.5–2 cubic yards of light material (mulch); 1 yard maximum of dirt/gravel due to weight limits
- Pickup truck (3/4 or 1 ton): 2–3 yards of light material; 1.5–2 yards of dirt/gravel
- Single-axle dump truck: 5–8 cubic yards
- Tandem-axle dump truck: 10–14 cubic yards (most common delivery truck)
- Tri-axle dump truck: 14–18 cubic yards
- Tractor-trailer dump: 20–30 cubic yards (large commercial projects only)
Maximum legal weight (around 25 tons in most US states) often limits the load before volume does, especially for heavy materials like concrete, asphalt, or wet dirt. A "10 yard" delivery of dirt might actually arrive with 7–8 yards because the truck hits its weight cap first.
Calculating Cubic Yards for Irregular Shapes
Real-world projects rarely match perfect rectangles. Here's how to handle the most common irregular shapes:
- Break it into pieces. Divide the area into rectangles, triangles, and trapezoids you can measure individually. Add the volumes together at the end.
- Average irregular widths. For a wedge-shaped area that's 6 ft wide on one end and 12 ft wide on the other, use the trapezoid formula: average width = (6 + 12) ÷ 2 = 9 ft.
- For circles and ovals. Use π × radius² for the area. For an oval, multiply π × (length/2) × (width/2).
- For sloped depth. If depth varies (like a sloped driveway), average the deepest and shallowest measurements: e.g., 8 inches deep at one end, 4 inches at the other = 6 inches average depth.
- Round up. Always pad your final estimate by 10–15% for irregular shapes — small calculation errors compound, and running short on delivery day is far worse than over-ordering by a yard.
Common Mistakes to Avoid
- Dividing by 3 instead of 27. A cubic yard is 3 ft cubed, not 3 ft squared. Always divide cubic feet by 27.
- Mixing units. Don't multiply 20 feet by 4 inches and call it square feet. Convert depth to feet first (4 ÷ 12 = 0.333), or use a tool that handles units.
- Forgetting the waste factor. Compaction, spillage, and uneven sub-grade can eat 5–15% of your material before it's where you need it. Pad accordingly.
- Ignoring weight limits. Heavy materials like concrete or wet dirt may need split deliveries due to truck weight caps. Confirm with your supplier.
- Using nominal lumber dimensions in volume math. A 2 × 4 board is actually 1.5 × 3.5 inches — easy to inflate volume estimates by 30% otherwise.
Buying Bulk Materials by the Yard
For projects needing more than half a cubic yard, bulk delivery is almost always cheaper than buying bagged. A 2 cubic foot bag of mulch retails around $4 — that's $54 per cubic yard equivalent. Bulk delivered mulch runs $25–40 per yard. The breakeven for hauling vs delivery is usually around 1 yard, depending on local pricing.
When ordering bulk, ask suppliers about minimum order quantities, delivery surcharges, and dump location requirements (some trucks need a 14-foot dump clearance). A typical bulk material order includes: $50–150 delivery fee, 1 ton minimum on most materials, and 30-minute unload window before wait fees kick in.