Cubic Yards Calculator

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How to Use This Cubic Yards Calculator

Pick the shape that matches your project area, enter your dimensions, adjust the waste buffer, and hit Calculate. That’s all there is to it.

Three shape tabs are available:

• Rectangle / Square for slabs, driveways, patios, raised beds, or any flat rectangular area
• Cylinders / Post Holes for concrete piers, sonotube footings, or circular pads
• Triangle for wedge-shaped fill areas, drainage swales, or odd lot corners

Each tab accepts mixed units. You can type your length in feet, your width in yards, and your depth in inches all at once. The calculator converts everything internally before running the math, so you don’t have to.

After entering dimensions, choose a material type if you need a weight estimate. The options cover the most common materials used on residential and light commercial jobs:

Material	Approx. Weight per Cubic Yard
Concrete	~4,050 lbs (~2.0 US tons)
Gravel / Crushed Stone	~2,700 lbs (~1.35 US tons)
Sand (Dry)	~2,600 lbs (~1.3 US tons)
Topsoil / Dirt	~2,200 lbs (~1.1 US tons)
Wood Mulch	~600 lbs (~0.3 US tons)

Then set the waste and compaction buffer using the slider (0% to 30%). The calculator defaults to 10%, which is a reasonable starting point for most pours.

If you have a supplier quote, drop the price per cubic yard or per US ton into the optional cost field. The calculator will multiply it out and give you a total material cost estimate.

Results show your volume in cubic yards, cubic feet, and cubic meters simultaneously.

What Is a Cubic Yard?

A cubic yard is a unit of volume equal to a cube that measures 3 feet on every side. That works out to 27 cubic feet, or roughly 202 gallons.

In construction, it’s the standard unit for ordering ready-mix concrete, topsoil, gravel, fill dirt, mulch, and similar bulk materials. Suppliers price these by the yard, which is why getting the number right before you call matters so much.

Cubic yards are also called “yards” informally on job sites. When a concrete dispatcher asks how many yards you need, they mean cubic yards.

The Core Formula

For a rectangular or square area, the calculation follows a straightforward path:

Volume (CY) = (Length × Width × Depth) ÷ 27

All three dimensions must be in feet before dividing by 27, since there are 27 cubic feet in one cubic yard.

Practical example. You’re pouring a 20-foot by 12-foot concrete patio at 4 inches thick.

• Convert 4 inches to feet: 4 ÷ 12 = 0.333 ft
• Multiply: 20 × 12 × 0.333 = 80 cubic feet
• Divide by 27: 80 ÷ 27 = 2.96 cubic yards

Add a 10% waste buffer: 2.96 × 1.10 = 3.26 cubic yards

Most concrete plants will round that to 3.5 yards and that’s what you’d order to avoid running short.

For cylinders, the formula uses the circular cross-section area:

Volume (CY) = π × (Diameter ÷ 2)² × Depth ÷ 27 × Quantity

So a 12-inch diameter post hole that’s 4 feet deep works out to: π × (0.5)² × 4 ÷ 27 ≈ 0.116 cubic yards per hole

Ten post holes of the same size: 1.16 cubic yards before waste.

For a triangular prism (a wedge shape), the formula is:

Volume (CY) = 0.5 × Base × Height × Depth ÷ 27

This covers situations like a tapered fill area, a drainage berm, or a triangular landscape bed.

Why the Waste Factor is Not Optional

Nearly every estimator, contractor, and concrete supplier will tell you to add at minimum 5% to 10% overage to any material order. The reasons are practical and compound quickly.

Subgrade variation. No earthwork is perfectly level. A subgrade that varies by half an inch across 20 feet can add several extra cubic feet of material before you even start.

Concrete spillage and slump loss. During chute or pump placement, some concrete is always lost at the edges, around form boards, or to overfill that gets scraped off.

Soil compaction ratios. If you’re filling or backfilling with dirt, loose excavated material compacts down significantly. Fill dirt typically has a compaction ratio of around 1.25 to 1.35, meaning you need roughly 25% to 35% more loose material than the finished volume requires.

Delivery minimums. Many ready-mix plants have a minimum order of 1 cubic yard. If your calculation comes to 0.8 yards, you’re paying for a full yard anyway.

Common waste factors by project type:

Project Type	Recommended Waste Buffer
Concrete slab on grade	5% to 10%
Concrete footings / piers	10% to 15%
Gravel base course	10% to 15%
Topsoil or fill dirt	15% to 25%
Mulch (landscape beds)	10%

If your subgrade is rough or your forms are not perfectly square, lean toward the higher end of each range.

Material Weights: Why they Matter for Budgeting

Volume tells you how much space the material fills. Weight tells you how many truck loads you’re dealing with and whether the price quote is apples-to-apples.

Concrete, gravel, and crushed stone are often sold by weight (per US ton) in quarry or ready-mix pricing, not purely by volume. If your supplier quotes you $35 per ton for gravel and you only know the cubic yardage, you need the bulk density of the material to convert.

The calculator does this conversion automatically once you select a material type.

A note on concrete specifically. The 4,050 lbs per cubic yard figure used here reflects typical normal-weight concrete made with standard aggregate. Lightweight concrete using expanded shale or pumice aggregate runs closer to 3,000 to 3,300 lbs per CY. Heavyweight concrete (used for radiation shielding or counterweights) can reach 5,500 to 6,000 lbs per CY. If you’re working with a non-standard mix design, verify the unit weight with your ready-mix supplier rather than relying on a generic density.

Topsoil and fill dirt weights vary more than most people expect. Moisture content is the main driver. Saturated fill dirt can weigh close to 3,000 lbs per CY. Dry sandy topsoil can be as low as 1,700 lbs per CY. The 2,200 lbs figure in this calculator represents a reasonable dry average for estimating purposes, but always confirm with your soil supplier for trucking and structural load calculations.

Common Projects and Realistic Material Quantities

Here’s a practical reference table to sanity-check your numbers before you order.

Project	Typical Dimensions	Approx. Cubic Yards Needed
10×10 concrete patio, 4″ thick	10 ft × 10 ft × 0.33 ft	~1.2 CY
20×20 concrete slab, 4″ thick	20 ft × 20 ft × 0.33 ft	~4.9 CY
Standard driveway (2-car), 4″ thick	20 ft × 40 ft × 0.33 ft	~9.9 CY
4″ gravel base under 20×20 slab	20 ft × 20 ft × 0.33 ft	~4.9 CY
Raised garden bed 8×4, 12″ deep	8 ft × 4 ft × 1 ft	~1.2 CY
10 post holes, 12″ dia × 4 ft deep	π × 0.25 × 4 × 10 ÷ 27	~1.2 CY
3″ mulch layer over 500 sq ft	500 sq ft × 0.25 ft ÷ 27	~4.6 CY

These figures don’t include waste. Always apply the appropriate buffer from the table above before placing your order.

Depth Conversion Reference: Inches to Feet

Depth is almost always measured in inches on-site, but the formula requires feet. This trips people up more than any other part of the calculation.

Depth in Inches	Decimal Feet
2″	0.167 ft
3″	0.250 ft
4″	0.333 ft
6″	0.500 ft
8″	0.667 ft
10″	0.833 ft
12″	1.000 ft
18″	1.500 ft
24″	2.000 ft

The cubic yards calculator handles this conversion automatically when you select “in” from the unit dropdown. But if you’re working through the math manually on paper, this table saves a step.

Cubic Yards vs. Cubic Feet: When to Use Each

Most bulk materials are sold and delivered by the cubic yard in the US. That’s the unit you’ll use when calling a concrete plant, ordering a fill-dirt delivery, or buying topsoil by the truckload.

Cubic feet shows up in a few specific places:

• Bagged materials at home improvement stores (mulch bags, potting soil, concrete mix) are labeled in cubic feet
• Smaller fill quantities that fall below the minimum delivery threshold
• Some landscaping supply catalogs list their products per cubic foot

Quick conversions to know:

• 1 cubic yard = 27 cubic feet
• 1 cubic foot = 0.037 cubic yards
• 1 cubic yard ≈ 0.765 cubic meters

If you’re buying bagged concrete mix (like 60-lb or 80-lb bags), each bag covers a fraction of a cubic foot. A 60-lb bag yields approximately 0.45 cubic feet. An 80-lb bag yields approximately 0.60 cubic feet. So for a slab that requires 4.9 cubic yards (132 cubic feet), you’d need roughly 220 bags of 80-lb mix, which is rarely economical compared to ready-mix delivery.

The crossover point where ready-mix becomes cheaper than bagged is usually around 1 cubic yard, sometimes less depending on local pricing.

Ordering Concrete: What Happens If You Get It Wrong

Under-ordering concrete is one of the more stressful situations on a job site. Here’s why:

Ready-mix concrete starts hydrating the moment water hits cement. Once a truck leaves the plant, you typically have 90 minutes to discharge the full load and finish the pour. If you run short, calling for a second truck mid-pour means a cold joint at the point where fresh concrete meets partially set concrete. Cold joints are structural weak points. Depending on the application, they may require engineering review or repair.

Over-ordering is far less of a problem. Extra concrete can be used for small ancillary pours, a small pad near the main slab, or it goes back to the plant with the truck. Plants typically charge a per-yard fee for returned concrete, but it’s a predictable cost.

The practical rule that most experienced contractors follow: round your calculation up to the nearest quarter yard, then add one more full yard as insurance on any pour larger than 5 yards.

Frequently Asked Questions (FAQs)

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All weight and density values in this calculator are representative averages for estimation purposes. Actual material weights vary by source, aggregate type, and moisture content. Confirm unit weights with your supplier for structural calculations or trucking load planning.

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Sources & References

U.S. Occupational Safety and Health Administration (OSHA). (2015). Trenching and Excavation Safety (OSHA 2226-10R). U.S. Department of Labor.

American Concrete Institute (ACI). (2013). ACI Education Bulletin E3-13: Cementitious Materials for Concrete. Farmington Hills, MI: ACI Committee E-701, Materials for Concrete Construction.

American Concrete Institute (ACI). ACI 302.1R-15: Guide for Concrete Floor and Slab Construction – Chapter 5. ACI Committee 302 (2015).

Virtual Design & Construction Institute (VDCI). Understanding Units of Measure for Concrete: Cubic Yards vs. Square Feet in Construction Planning. VDCI Learning Resources.

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Technical Basis

This calculator is developed using verified formulas, industry standards, and authoritative reference materials. Data is cross‑checked with ASTM specifications, ASHRAE Fundamentals, CIBSE Guide C, NEC tables, ACI guidelines, Crane TP‑410, and widely accepted engineering textbooks. All calculations follow standard equations used in construction, engineering, and building‑code practices.

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Disclaimer

These tools provide estimates based on standard formulas and reference data. Actual requirements may vary depending on local codes, material variations, and project conditions. For final design decisions, consult a licensed professional.

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