How to Figure Out Yards of Concrete - The Complete 2026 Guide

How to Figure Out Yards of Concrete - The Complete 2026 Guide

Whether you are pouring a backyard patio, a garage floor, or a full driveway, the first question every DIYer and contractor asks is the same: how do I figure out yards of concrete for this project? Getting this number right is the difference between a smooth pour and an expensive mistake. Order too little concrete and you get a cold joint - a weak seam that compromises the entire slab. Order too much and you waste hundreds of dollars on material you will never use.

This guide gives you the exact formula, real-world examples, and pro tips so you can figure out yards of concrete with confidence - no guesswork required.

The Basic Formula: Length × Width × Depth

To figure out yards of concrete, you need three measurements:

• Length - in feet
• Width - in feet
• Depth (thickness) - in inches, converted to feet

The formula is simple:

Step 1: Multiply length × width × depth (in feet) = cubic feet
Step 2: Divide cubic feet by 27 = cubic yards

That is it. One cubic yard of concrete covers 27 cubic feet. Every time you need to figure out yards of concrete, this is the math that gets you there.

Real-World Example: 20×20 Driveway at 6 Inches Thick

Let us walk through a common project so you can see the formula in action.

Step 1: Convert thickness to feet: 6 inches ÷ 12 = 0.5 feet

Step 2: Calculate cubic feet: 20 ft × 20 ft × 0.5 ft = 200 cubic feet

Step 3: Convert to cubic yards: 200 ÷ 27 = 7.41 cubic yards

So to figure out yards of concrete for a 20×20 driveway at 6 inches thick, you need 7.41 cubic yards before waste.

Always Add a Waste Factor

Here is where most DIYers come up short. When you figure out yards of concrete, you must add 10% extra for spillage, uneven ground, form movement, and over-excavation. Concrete suppliers do not sell fractions neatly - and running short mid-pour is a disaster.

Waste calculation: 7.41 yd³ × 1.10 = 8.15 yd³

Round up to 8.25 or 8.5 cubic yards when ordering. That small buffer protects you from the most common and costly mistake in concrete work.

Quick Reference: Common Project Sizes

Use this table to quickly figure out yards of concrete for standard projects (includes 10% waste):

Project	Dimensions	Thickness	Cubic Yards (with waste)
Small patio	10×10	4"	1.37
Medium patio	12×12	4"	1.97
Large patio	16×16	4"	3.51
1-car garage	12×20	6"	4.88
2-car garage	20×20	6"	8.15
Small driveway	10×20	6"	4.07
Standard driveway	20×24	6"	9.77
Sidewalk section	3×30	4"	1.22

These numbers give you a fast way to figure out yards of concrete without doing the math every time. But always double-check with your actual dimensions.

How to Figure Out Yards of Concrete for Irregular Shapes

Not every project is a perfect rectangle. L-shaped patios, circular pads, and tapered slabs require a different approach. Here is how to figure out yards of concrete for irregular shapes:

L-Shaped Slabs: Break the shape into two rectangles. Calculate each separately, then add them together. For example, an L-shaped patio that is 10×12 plus 8×8 = 120 + 64 = 184 sq ft. Multiply by depth and divide by 27.

Circular Pads: Use π × radius² for area. A 12-foot diameter circle has a radius of 6 feet. Area = 3.14159 × 36 = 113.1 sq ft. At 4 inches thick: 113.1 × 0.333 ÷ 27 = 1.40 cubic yards (before waste).

Triangular Areas: Use (base × height) ÷ 2 for area, then proceed with the standard formula.

The key principle is the same: break complex shapes into simple ones, figure out yards of concrete for each, and sum the totals.

Cost Per Cubic Yard in 2026

Once you figure out yards of concrete needed, the next question is cost. In 2026, ready-mix concrete pricing varies by region:

• National average: $155 – $195 per cubic yard
• High-cost markets (CA, NY, WA): $200 – $260 per cubic yard
• Low-cost markets (Midwest, South): $130 – $165 per cubic yard

Additional costs to factor in:

• Delivery fee: $60 – $120 per load (some suppliers include this in the per-yard price)
• Short-load fee: Orders under 8–10 yards often carry a $50–$150 surcharge
• Weekend/after-hours delivery: $30 – $80 extra
• Fiber mesh additive: $10 – $20 per yard (optional reinforcement)

For our 20×20 driveway example (8.25 yd³ with waste):

8.25 yd³ × $175/yd³ = $1,444 for concrete + $80 delivery = $1,524 total material cost

DIY vs Professional: What to Expect

Knowing how to figure out yards of concrete is the first step. Deciding whether to DIY or hire a pro is the next.

DIY is realistic for: Projects under 100 square feet, simple rectangular shapes, and when you have 1–2 helpers. You will save 40–60% on labor but invest significant time and physical effort.

Hire a pro for: Driveways, garage floors, anything over 200 square feet, projects requiring finishing (broom, stamp, or stain), and any structural application. Professional installation typically runs $6 – $12 per square foot installed.

For the 20×20 driveway example: 400 sq ft × $8/sq ft = $3,200 installed versus ~$1,500 in materials for DIY.

Common Mistakes When Figuring Out Yards of Concrete

Even experienced DIYers make these errors. Avoid them:

• Forgetting to convert inches to feet: 6 inches = 0.5 feet, not 6 feet. This mistake multiplies your order by 12×.
• Skipping the waste factor: Always add 10%. Running short mid-pour costs far more than the extra yard.
• Measuring the surface, not the excavation: Ground is rarely level. Measure at multiple points and use the deepest measurement.
• Ignoring form thickness: Wood forms take up space. A 2×6 form is actually 5.5 inches wide, not 6.
• Ordering exact yardage: Suppliers deliver in quarter-yard increments. Round up, not down.

Use Our Free Calculator to Instantly Figure Out Yards of Concrete

While the formula is straightforward, doing it by hand for multiple projects gets tedious. Our free concrete yardage calculator lets you enter your exact dimensions and thickness, then instantly shows you cubic yards, cubic feet, bag counts, and cost estimates - all with the waste factor already included.

It is the fastest way to figure out yards of concrete without any math errors. Whether you are planning a small sidewalk or a full driveway, the calculator gives you accurate numbers in seconds so you can order with confidence.

FAQ

How do I figure out yards of concrete for a circular slab?

Calculate the area using π × radius², multiply by depth in feet, then divide by 27. Add 10% waste. For a 10-foot diameter circle at 4" thick: 78.5 sq ft × 0.333 ft ÷ 27 = 0.97 yd³ + 10% = 1.07 yd³.

How many 80-lb bags equal one cubic yard?

One cubic yard requires approximately 45 bags of 80-lb concrete mix (each bag yields 0.60 cubic feet, and 27 ÷ 0.60 = 45). For our 20×20 driveway example (8.25 yd³), that is 372 bags - which is why ready-mix delivery is strongly recommended for projects over 2 cubic yards.

Can I figure out yards of concrete using square footage alone?

You need thickness too. A general rule of thumb: at 4 inches thick, 1 cubic yard covers 81 square feet. At 6 inches thick, 1 cubic yard covers 54 square feet. Divide your square footage by these numbers to quickly estimate.

What if my slab has varying thickness?

Measure the thickness at multiple points, calculate the average, and use that in the formula. For example, if one end is 4" and the other is 6", use 5" as your thickness. This gives you a close enough estimate for ordering purposes.

Start Planning Your Concrete Project Today

Now you know exactly how to figure out yards of concrete for any project - from a small garden path to a full two-car driveway. The formula is simple, the math is straightforward, and with a 10% waste buffer, you will never run short again.

The fastest path from planning to pouring is using a dedicated tool. Our concrete yardage calculator handles all the math instantly so you can focus on the pour, not the paperwork.