How Much Concrete Do I Need for a Patio?
If you're planning a new patio, one of the most important things to work out before starting is how much concrete you'll actually need.
Order too little and you risk running short part-way through the job. Order far too much and you'll potentially be paying for concrete you don't need.
Fortunately, estimating the amount of concrete required for a patio is relatively straightforward once you know the length, width and depth of the area you're working with.
In this guide, we'll explain how to calculate your concrete requirement, look at a few typical examples and cover some of the other things worth considering before arranging your delivery.
How Do You Calculate Concrete for a Patio?
Concrete is normally ordered in cubic metres (m³).
For a simple rectangular patio, the basic calculation is:
Length × Width × Depth = Volume of Concrete
The important thing is to make sure all three measurements are in metres.
For example, if your proposed patio measures:
4m long × 3m wide × 0.1m deep
The calculation would be:
4 × 3 × 0.1 = 1.2m³
So, based purely on those dimensions, the area would contain 1.2 cubic metres of concrete.
If you'd rather not calculate it manually, you can enter your measurements into our online Concrete Calculator to get an initial estimate.
How Much Concrete Do I Need for a 3m x 3m Patio?
Let's look at another simple example.
For a patio measuring 3m × 3m, using a hypothetical depth of 100mm (0.1m) for the purpose of calculating volume:
3 × 3 × 0.1 = 0.9m³
That gives a calculated volume of 0.9 cubic metres.
Change the depth, however, and the amount of concrete required changes too.
At 75mm (0.075m), the same 3m × 3m area would have a volume of:
3 × 3 × 0.075 = 0.675m³
That's why it's important to use the actual specified depth for your particular project rather than simply estimating from the surface area.
How Much Concrete Do I Need for a 4m x 5m Patio?
For a larger 4m × 5m patio, again using 100mm purely as an example:
4 × 5 × 0.1 = 2m³
So the calculated volume would be 2 cubic metres of concrete.
This demonstrates how quickly the quantity can increase as the size of the patio grows.
Mixing a very small quantity of concrete yourself may be manageable, but once a project requires a significant volume, having concrete delivered can save a considerable amount of time and physical effort.
Our recent guide Can You Order Small Amounts of Concrete? looks at this in more detail.
How Thick Should Concrete Be for a Patio?
There isn't one concrete depth that's automatically suitable for every patio.
The appropriate construction will depend on factors including the intended use of the area, ground conditions, the design of the patio and what will ultimately be installed or placed above it.
A domestic seating area, for example, doesn't necessarily have the same requirements as an area expected to carry considerably heavier loads.
If your patio or slab forms part of a structural project, you should always follow the specification provided by your builder, architect or structural engineer.
The examples in this article use particular depths simply to demonstrate how concrete volume is calculated rather than to specify how your patio should be constructed.
Should I Order Extra Concrete?
A calculation based on perfect dimensions doesn't always reflect what you'll find on a real site.
Excavations aren't necessarily completely level, and small variations in depth across an area can increase the actual volume required.
For example, an excavation intended to be 100mm deep may contain sections that are slightly deeper.
This is why accurate measurement and good preparation are important.
If you're unsure how much concrete you need, speak to the William The Concreter team before ordering. We can discuss your measurements and the project with you.
You can also use our Concrete Calculator as a starting point.
What If My Patio Isn't Rectangular?
Not every patio is a perfect rectangle.
If you have an L-shaped or irregular area, one simple approach is to divide it into a number of smaller rectangular sections.
Calculate the volume of each section separately using:
Length × Width × Depth
Then add the individual figures together.
For particularly unusual shapes or varying depths, estimating the exact quantity can become more difficult. In these circumstances, it's worth discussing the project when arranging your concrete supply.
Ready-Mix or Volumetric Concrete for a Patio?
Depending on your project, concrete can be supplied using ready-mix or volumetric concrete.
Ready-mix concrete is produced to the required specification and delivered ready for placement.
A volumetric mixer carries the constituent materials separately and mixes the concrete on site. One advantage of this approach is flexibility where the precise quantity required may be more difficult to predict.
This can be useful for some domestic projects where excavations aren't perfectly uniform.
We've explained the differences in our guide to Ready-Mix vs Volumetric Concrete, as well as our more detailed article When Should You Choose Volumetric Concrete?
How Do You Get Concrete Into a Back Garden?
For many patio projects, calculating the amount of concrete is only half the challenge.
You also need to think about how the concrete will reach the patio.
If the project is at the rear of your property, the delivery vehicle may not be able to get anywhere near the actual pour.
Depending on the property, quantity and distance involved, concrete pumping can provide a practical way of moving concrete from the delivery vehicle to a difficult-to-access area.
We've covered this specifically in our new guide: Can Concrete Be Delivered to My Back Garden?
William The Concreter also operates its own concrete pumping equipment, allowing us to coordinate concrete supply and pump hire where required.
Prepare Your Patio Before the Concrete Arrives
Once you've calculated your quantity and arranged delivery, make sure the site itself is ready.
Depending on the project, preparation may include excavation, preparing and compacting the appropriate sub-base, installing formwork and positioning any specified reinforcement.
You should also make sure access has been considered and that the people and equipment required to place and finish the concrete are ready before the delivery arrives.
Our guide How Do You Prepare a Site Before Concrete Is Delivered? provides a more detailed checklist.
Patio Concrete Delivery Across East Sussex & Kent
William The Concreter supplies concrete for patios, garden projects, extensions, shed bases and other domestic projects throughout East Sussex and Kent.
From our base in Battle, we regularly deliver across Hastings, Bexhill, Rye, Eastbourne, Hailsham, Robertsbridge, Cranbrook, Tunbridge Wells, Tonbridge and surrounding areas.
With more than 40 years' experience, our team can help you arrange the appropriate concrete supply for your project, with ready-mix concrete, volumetric concrete and concrete pump hire available.
Need Concrete for Your Patio?
If you're planning a new patio and aren't sure how much concrete you'll need, start by measuring the length, width and required depth of the area.
You can then use our online Concrete Calculator to get an initial estimate.
If you're still unsure, just speak to us. Tell us the dimensions of your patio, where you're located and what access to the project is like, and our friendly and helpful team can discuss your needs.
Call us on 01424 775388 or contact us online.
