The Basics of Ordering Concrete
Last Updated February 2026
If you’re getting ready to order a ready-mix concrete delivery for a residential project, knowing a few basics ahead of time can save you money, delays, and frustration on pour day. Whether you’re a homeowner tackling a driveway or patio, or a contractor coordinating a small job, understanding how concrete is ordered helps everything go more smoothly. This guide walks through the key things you’ll be asked when scheduling a concrete delivery and what those choices actually mean.
What Do I Need to Know Before Ordering Concrete?
Before ordering ready-mix concrete, you should:
Measure your project and calculate total cubic yards (order 4–8% extra)
Choose the correct concrete strength (PSI)
Specify the slump for workability
Confirm whether the mix is for interior or exterior use
Plan how the concrete will be unloaded
Provide a proper washout area for the truck
Below, we’ll break down each of these items in more detail so you know exactly what to expect when placing your order.
How Much Concrete Do I Need to Order?
How much concrete do you need? Once you are confident in your measurements, figuring out how much ready-mix you need is easy thanks to the literally hundreds of concrete calculators you can find online.
Here is a calculator for square and rectangular areas.
Use this calculator to estimate how many cubic yards of concrete you’ll need for square or rectangular areas such as driveways, patios, sidewalks, and slabs.
Disclaimer - this calculator is intended for estimating purposes only. Rocket Concrete Company is not responsible for any discrepancies in yardage based on the information provided.
Here is a calculator for round areas.
Use this calculator to estimate concrete quantities for round areas such as footings, piers, sonotubes, or circular pads.
Disclaimer - this calculator is intended for estimating purposes only. Rocket Concrete Company is not responsible for any discrepancies in yardage based on the information provided.
Contractors will recommend ordering anywhere from 4% - 8% extra to cover discrepancies in the surface of your job site, spillage, settling, spreading of your forms, etc. Both the above calculators have an 8% buffer included in the final number. If this is your first time working with concrete, here is a good post to help determine if you need a ready-mix delivery.
Concrete Strength (PSI): What It Means and What to Choose
This is the compressive strength of the cured concrete rated in Pounds Per Square Inch (PSI). We wrote a more detailed post on this you can read here. The standard mixes are 3000 psi, 3500 psi, and 4000 psi. Higher is available if your project requires a stronger mix.
For most residential driveways and patios in the Lake Norman and Charlotte area, a 3500 PSI mix with a 5” slump is often a good starting point. This provides a good balance of strength for vehicle traffic while still being workable enough for proper placement and finishing. Many customers will increase to 4000psi for driveways and workshop slabs, this gives some cushion for a larger vehicle or heavy equipment.
Concrete Slump Explained (Workability & Strength Tradeoffs)
Slump is how we refer to the consistency and work-ability of the concrete mix. Slump is referenced from 1-10 inches. This could be a whole post on its own. But for now, the important thing to know is a lower slump number means the concrete is thicker and more difficult to work with.
A concrete slump test being performed, on the left is a “high slump” on the right is a “low slump”
A higher number means it will be thinner and easier to spread around in the forms. For an average residential job a 5” slump will do just fine. It is always best to have the slump set from the batch plant. We can adjust the slump on-site by adding water, but this can damage your mix. Adding 1 gallon of water per 1 yard of concrete can lower the strength up to 200 psi.
Interior vs. Exterior Concrete Mixes
The type of concrete mix will vary depending if the project is indoors or outdoors. Concrete used for an exterior application will often require entrained air. Entrained air is tiny air bubbles in the ready-mix that helps reduce the chance of cracking during the freeze / thaw cycle of the seasons. Interior mix usually does not need to have entrained air due to not being exposed the elements. This post isn’t meant to cover the final surface finish (see this post for more information on exterior mixes), but keep in mind that it is not recommended to slick finish an entrained mix. So if you are intending to have a smooth or polished finish don’t order with entrained air.
How Will the Concrete Be Unloaded?
We will ask if your job site is accessible to the mixer truck, if there are any obstacles or hazards, and how you are going to unload the concrete from the truck. This previous post has all the information you will need to help you answer this question. Long story short, you can pour direct from the truck, use wheelbarrows, rent a Georgia Buggy, or hire a pump truck. The important things to consider when choosing a method are; the time it will take to unload, the safety of the truck and job site, and how accessible are the forms with the option you choose.
Concrete Truck Washout Requirements
All concrete delivery companies require the job site to provide an area for the driver to washout the truck after pouring. It is illegal to wash concrete into the street or storm drain. We require a contained area that will not allow the liquid to seep or drain into surrounding areas. Good options are a wheelbarrow or even a cheap plastic kiddie pool.
Frequently Asked Questions About Ordering Concrete
How much extra concrete should I order?
Most contractors recommend ordering 4–8% extra concrete to account for uneven subgrade, form spread, minor spillage, and variations in site conditions. Ordering a small buffer is usually cheaper than needing an additional delivery. The calculators above have a built in buffer to the calculation.
Can concrete be made wetter on site?
Concrete slump can be adjusted on site by adding water, but doing so can reduce strength. Adding approximately one gallon of water per cubic yard can lower compressive strength by up to 200 PSI.
What PSI concrete do I need for a driveway or patio?
Most residential driveways and patios use 3000–4000 PSI concrete, depending on vehicle traffic, soil conditions, and local requirements.
What happens if I order too little concrete?
If you run short, it can lead to cold joints or require an additional delivery, which is often more expensive and disruptive than ordering a small buffer up front.
When you’re ready, give us a call 980-281-3131. We’d be honored to be your concrete supplier. Rocket Concrete provides ready-mix concrete delivery throughout the Lake Norman area, including Mooresville, Statesville, Troutman, Huntersville, Cornelius, Denver, Concord, and select areas of Charlotte depending on project size and access.
