How do I know how much concrete to order?


Whatever job you’ve got planned, it’s always important to order the correct quantity of materials. 

That definitely applies where concrete is concerned. 

Ask for too little, and you’ll have a temporarily unfinished job. 

If the first batch sets before you have a chance to add the rest, you’ll end up with a seam in the finish known as a cold joint. 

While this isn’t a problem for most jobs, it isn’t ideal for structural applications. 

Order too much concrete, and you’ll end up spending more money than you needed. 

It’s easy for costs to spiral beyond initial estimates, so if you have too much you’ll not only impact a project’s budget, but may also have to pay for the surplus to be disposed of safely.

First, let’s define exactly what concrete is…

What is concrete?

Concrete is not the name of a particular material, rather it’s a mix of them. 

Broken stone, cement, gravel and other materials are mixed with water which then hardens to form concrete. 

The hardness and density of the product depends on what’s included. 

Mixing different materials together results in a chemical reaction that causes the workable mixture to harden. 

The ratio of water to cement matters, so too does the paste quality which needs to be free of empty spaces. 

To successfully use concrete, you must know exactly the consistency you need, when it needs to be made, and how to store and apply it before it hardens.

It might sound like a complicated process, but a specialist like Goodmix can provide the specialist advice you need for a project.

How to calculate the metric volume of concrete you’ll need

If you’ve never used concrete before, judging what to order might seem like something of a minefield. 

However, it’s a relatively straightforward process.  

If the area that you’re looking to concrete is a regular square or rectangle, calculating the correct amount you require is fairly simple.  

You need to measure the width, depth and length before multiplying them together. 

If the space you’re looking to concrete is irregular, you’ll need to break it up into regular shapes and make individual calculations for each space. 

Round, circular, prism and other irregular shapes are trickier to measure. 

It’s important to ensure all the units of measurements you use are metric and uniform.  

It might also be prudent to add an extra five to 10 per cent to ensure that you have enough.

Getting your order right

As well as knowing the volume of concrete you require, there are other factors you need to consider. 

Concrete comes in a range of different types and densities. 

Your choice will depend on the job. 

Colours and texture can vary too, so you should have some idea about the finish you’d prefer before you order. 

Those variations influence the price.

Concrete density 

There are regulations that determine the density of concrete needed for different areas and building projects. 

A house foundation, for instance, that only needs to withstand foot traffic doesn’t require the same density as a garage floor or a driveway.  

If you are concreting a goods yard used on a daily basis by heavy vehicles, the density would need to be tough enough to cope.

Concrete type

Concrete grade is the minimum compressive strength rating 28 days after the concrete was poured.

The grading systems reflect a job that the concrete is required to do, making it easier to order the correct strength and density.

  • C7/8 – usually used for domestic foundations, kerbing, cavity filling and haunching.
  • C10 – has a wide range of both commercial and domestic uses. These include drainage works, trench filling, floor binding, garden walls and non-load bearing walls.
  • C15 – the ideal mix for use on concrete floors that don’t contain embedded metal. Mostly used in domestic construction situations. These include small walls, a bare flooring finish, paths, paving, shed foundations and garden walls.
  • C20 – mainly used in domestic and lightweight commercial construction projects. It’s often used for farmyard slabs in areas of lighter traffic, patio foundations and slab foundations for extensions and garages.
  • C25 – has a wide range of commercial and domestic applications including trench filling, flooring, foundations, groundworks, kerbing and patio bases.
  • C30 – a widely used concrete type that is principally used in outdoor projects that require a degree of strength. These include house extensions, paving, home bases, pavements, driveways and external slabs.
  • C35 – this is a heavy-duty concrete mix that’s known for its high strength and ability to support heavy loads. It’s mostly used in large scale commercial applications such as reinforced bases for commercial buildings, agricultural storage areas, outdoor pavings where heavy vehicles are used and external slabs.
  • C40 – a real heavy-duty density of concrete that is used in the toughest of applications. HGV car parks, structural beams, roadworks, septic tank foundations and agricultural yard construction will all make use of this grade.

How we work

Goodmix Concrete is a leading provider of ready mix and barrow mix concrete across the north west.

If you’re looking for advice about a project or the type and volume of concrete you require, then we can help. 

We supply material for both DIY and commerical projects.

All ready mix concrete is delivered on time and poured on site to the customer’s specification. 

This eliminates issues around waste, ensuring the customer only pays for the concrete they need. Goodmix only use aggregates that have come direct from a quarry, not lower quality recycled products.

To find out more about the how we can help with your domestic or commercial project, why not contact us?