So: How Much Ready Mix Concrete Do You Really Need?

Every concrete project starts with the same question: how many cubic yards do I need to order? Whether you are pouring a driveway, setting footings for a new deck, or laying a patio slab, getting the quantity right saves you money and keeps your project on schedule.

Use EcoTerra’s free ready mix calculator below to estimate the cubic yards required for your project. Enter your dimensions, and we’ll do the math: no sign-up, no guesswork.


Pro Tip: Always add 5–10% to your calculated total to account for uneven subgrade, spillage, and slight measurement variations. Running short mid-pour is far more expensive than ordering a little extra.

Ready Mix Calculator

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Estimated cubic yards.

How to Measure for Concrete

Accurate measurements are the foundation of a successful pour. Here is how to measure the three most common project types:

Slabs (Patios, Driveways, Garage Floors)

Measure the length and width of the area in feet, then determine the thickness in inches. Most residential slabs are 4 inches thick for walkways and patios, or 5–6 inches for driveways and garage floors that need to support vehicle weight. Multiply length by width by thickness (converted to feet), then divide by 27 to get cubic yards.

Footings & Foundations

Footings are typically 12–24 inches wide and 6–12 inches deep, depending on local building codes and the load they need to support. Measure the total linear footage of the footing, then multiply by its width and depth (both in feet) and divide by 27.

Columns & Round Forms

For round forms like Sonotubes, measure the diameter and height in inches. The formula uses pi (π) to calculate the volume of a cylinder: multiply π by the radius squared by the height, then convert to cubic yards. Our calculator handles this automatically when you select the column shape.

Quick Reference: Common Project Sizes

Project
Dimensions
Thickness
Approx. Yards

Sidewalk (3’ x 30’)

3’ x 30’
4″

~1.1 yards

Small Patio (10’ x 10’)
10’ x 10’

4″

~1.25 yards

Large Patio (12’ x 20

12’ x 20’

4″

~3.0 yards

Single-Car Driveway (10’ x 20’)

10’ x 20’

5″

~3.1 yards

Two-Car Driveway (20’ x 20’)

20’ x 20’

5″

~6.2 yards

Garage Floor (20’ x 24’)

20’ x 24’

6″

~8.9 yards

Shed Slab (10’ x 12’)

10’ x 12’

4″

~1.5 yards

Note: These estimates do not include the recommended 5–10% waste buffer. Always round up when placing your order.

What Does a Cubic Yard of Concrete Look Like?

A cubic yard of concrete is a volume of 3 feet by 3 feet by 3 feet: 27 cubic feet in total. Poured on a perfectly flat surface at 4 inches thick, one cubic yard covers approximately 81 square feet (roughly a 9’ x 9’ area). A standard ready mix truck typically carries 8–10 cubic yards per load, and a cubic yard of wet concrete weighs approximately 4,000 pounds.

For a quick mental shortcut on 4-inch slabs: divide your total square footage by 81 to get an approximate cubic yard count. Then add your waste buffer.

When to Order Ready Mix vs. Bagged Concrete

For projects under 1 cubic yard (roughly a 10’ x 10’ slab at 4 inches), bagged concrete from a hardware store can be a practical option: just keep in mind that one cubic yard requires approximately 45 bags at 80 pounds each, which is over 3,600 pounds of material to handle by hand.

For anything larger than 1 yard, ready mix delivery is almost always the better choice. It saves hours of labor, delivers consistent mix quality, and eliminates the risk of cold joints caused by staggered pours from batch mixing.

EcoTerra’s Advantage: Volumetric Mixing

Unlike traditional drum trucks that arrive with a pre-mixed load, EcoTerra’s volumetric mixers produce fresh concrete on your job site. This means you pay only for what you use: no short-load fees, no wasted material, and no pressure from the 90-minute delivery window that makes traditional ready mix a race against the clock. If your pour takes longer than expected, the concrete in our truck is still dry until you need it.

Tips for Ordering the Right Amount

  1. Measure twice. Use a tape measure on every dimension. Eyeballing leads to costly surprises on pour day.
  2. Check your subgrade. Uneven ground means some areas will be thicker than planned. If your base varies by even half an inch, total volume increases significantly over a large slab.
  3. Add 5–10% for waste. Spillage, overfill, and form inconsistencies always consume more material than you expect.
  4. Round up, not down. Coming up short mid-pour risks cold joints, project delays, and a second delivery fee that far exceeds the cost of an extra quarter yard.
  5. Confirm the mix design. Standard residential work uses 3,000–3,500 PSI. Driveways and high-traffic areas benefit from 4,000 PSI or higher.
  6. Schedule ahead. Most concrete suppliers need 24–48 hours of advance notice for standard orders and longer for specialty mixes. During peak season (April through October), book early to lock in your delivery window.

Frequently Asked Questions

Calculating & Ordering

Multiply the length, width, and thickness of your project (all in feet) to get the volume in cubic feet, then divide by 27 to convert to cubic yards. For example, a 10’ x 20’ driveway at 5 inches thick works out to about 3.1 cubic yards. Always add 5–10% to cover waste and subgrade variation.

At a standard 4-inch thickness, one cubic yard covers approximately 81 square feet. At 6 inches thick, it covers about 54 square feet. The thicker the pour, the less area each yard covers.

Running short is one of the most expensive mistakes in concrete work. You risk cold joints where the two separate pours do not bond properly, crew downtime while waiting for a second delivery, and an additional delivery charge. In some cases, the entire slab may need to be torn out and redone. This is why we recommend always ordering slightly more than your calculated total.

Most traditional concrete suppliers have a minimum delivery of 1 cubic yard, and they charge short-load fees when orders fall below 3-5 yards. With EcoTerra’s volumetric trucks, you pay only for the concrete you actually use, which makes smaller pours far more cost-effective.

Plan to call at least 24–48 hours ahead for standard orders. During peak construction season (April through October), scheduling a week or more in advance is recommended. Specialty mixes may require additional lead time.

Concrete Basics

PSI (pounds per square inch) measures concrete’s compressive strength after a 28-day cure. For most residential patios, walkways, and interior slabs, 3,000–3,500 PSI is standard. Driveways and garage floors benefit from 4,000 PSI. Commercial or heavy-duty applications may require 4,500 PSI or higher. Our team can recommend the right mix for your project.

Cement is one ingredient in concrete: it is the powder (typically Portland cement) that acts as a binding agent. Concrete is the finished product made by combining cement with water, sand, and gravel (aggregate). Saying “cement driveway” is a common shorthand, but what you are actually pouring is concrete.

Concrete reaches enough strength to walk on within 24–48 hours and can typically support vehicle traffic after 7 days. However, concrete continues to strengthen over time and reaches its rated PSI at approximately 28 days. Full curing can continue for months. During this period, keeping the surface moist helps achieve maximum strength.

Slump measures how workable the concrete mix is. It is tested by filling a 12-inch cone with fresh concrete, lifting the cone, and measuring how many inches the concrete settles. Most residential pours use a 4-inch slump. Higher slump (more water) is easier to work with but can reduce strength. Admixtures called water reducers can increase workability without sacrificing strength.

EcoTerra & Volumetric Mixing

No. Because our volumetric trucks mix concrete on-site, we meter the exact amount you need. There is no pre-mixed load to commit to and no penalty for ordering less than a full truck. You pay for the concrete you use.

Traditional ready mix is batched at a plant and loaded wet into a drum truck. Once mixed, it must be delivered and poured within roughly 90 minutes before it begins to set. Volumetric mixing carries the raw materials (cement, water, sand, and aggregate) separately on the truck and produces fresh concrete on your job site. This eliminates the time pressure, reduces waste, and gives you precise control over how much concrete is produced.

Yes. One of the advantages of volumetric mixing is the ability to adjust the mix on the fly. If you need a different PSI strength or want to add a feature like fiber reinforcement partway through the job, our operator can adjust the mix right at the truck.

We deliver ready mix concrete from two locations. Our Santa Rosa yard at 175 Scenic Ave serves Sonoma County, including Petaluma, Rohnert Park, Sebastopol, Windsor, Healdsburg, and surrounding communities. Our Richmond yard at 115 Brookside Dr serves the East Bay and Contra Costa County, including El Cerrito, San Pablo, Berkeley, Pinole, Hercules, Martinez, Walnut Creek, and Concord.

Cost & Waste

Concrete pricing varies by region, mix design, and delivery distance. In California, standard 3,000 PSI ready mix typically falls in the range of $190–$220 per cubic yard for full truckloads, with additional fees for short loads, specialty mixes, and extended delivery distances. Contact EcoTerra for a current quote specific to your project and location.

For very small projects (under 1 cubic yard), bagged concrete can be comparable in cost. However, one cubic yard requires about 45 bags at 80 pounds each, which is over 3,600 pounds of lifting and mixing. Above 1 yard, ready mix delivery is almost always more cost-effective, and it delivers far more consistent quality than hand-batching.

Leftover concrete can be poured into forms for stepping stones, used to fill low spots, or allowed to cure and then recycled as fill material. With EcoTerra’s volumetric trucks, waste is minimal because we mix only what your project requires, so leftover material is rarely an issue.

Yes. In addition to ready mix concrete, EcoTerra supplies Recycled Aggregate including recycled Class II Aggregate Base, recycled sand, and recycled drain rock from both our Santa Rosa and Richmond locations. These products offer Caltrans-compliant performance at a lower cost than virgin materials while diverting construction waste from landfills.