Getting the quantity right matters. Order too little and your pour can be disrupted. Order too much and you risk unnecessary waste and extra cost. The best approach is to measure carefully, calculate the volume in cubic metres, and allow a small margin for uneven ground, spillage, or formwork variation.
Use the online calculator, then request a quote to plan your pour with confidence.
Start with the shape of the area
Most concrete jobs fall into one of a few basic shapes:
- Rectangle or square
- Circle
- Strip footing or trench
- Slab with multiple sections
If your area doesn’t fit neatly into any of these, don’t try to force a single calculation. Instead, split it into smaller rectangles or sections, work out the volume of each one, and then add the totals together.
Measuring common concrete jobs
Slabs and bases
For a slab, base, patio, or driveway, you’ll need three measurements:
- Length
- Width
- Thickness
Footings and trenches
Footings work a little differently, since you’re measuring the trench rather than a flat surface:
- Total length of trench
- Width of trench
- Depth of trench
Circular areas
For circular slabs, measure the radius rather than the diameter. Using the wrong one will throw your entire calculation off.
Add a sensible allowance
Measurements on site are rarely perfectly exact, so it’s worth building in a small margin for:
- Uneven sub-base
- Minor spills
- Formwork movement
- Variation in excavation depth
Keep that allowance modest and controlled. A careful, considered measurement will always serve you better than simply guessing high to be safe.
Measure in sections for better accuracy
When a project includes more than one area, it’s best to calculate each section on its own rather than estimating the whole job in one go. For example:
- Main slab: 4 m × 3 m × 0.1 m = 1.2 m³
- Path: 6 m × 1 m × 0.1 m = 0.6 m³
Total = 1.8 m³
Breaking the job down this way is almost always more accurate than trying to picture the entire area at once.
Why exact quantities matter
Getting your measurements right helps you:
- Reduce waste
- Control cost
- Keep the pour running smoothly
- Order the right amount for the job
This is especially valuable with volumetric on-site batching, where concrete is mixed fresh on the day and can be adjusted precisely to the volume you actually require.
Common mistakes to avoid
A few errors come up again and again:
- Forgetting to convert mm to metres
- Measuring only one point where ground levels vary
- Guessing depth instead of checking it
- Treating irregular areas as one simple shape
- Ordering without any allowance at all
Avoiding these goes a long way toward getting your quantity right the first time.
Key takeaways
- Measure carefully and calculate everything in cubic metres.
- Convert all depths into metres before working out volume.
- Break complex areas into smaller sections for a more accurate total.
- Use the online calculator, then request a quote to book your delivery.
If you want to double-check your figures, use our online calculator and get in touch to discuss your project and schedule a delivery.