Concrete calculator
Use our Concrete Calculator to quickly estimate the volume and weight of concrete necessary to cover a given area.
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If you have any doubts about the amount of concrete required for your project, feel free to contact us. Our team is ready to provide expert advice and accurately determine the precise material needed.
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Recommended Extra Allowance
Our concrete calculator offers approximate calculations. Actual conversions may vary due to factors like material properties, volume estimation, waste, and project-specific conditions.
When calculating your concrete requirements for trenches and foundations, we recommend considering the following.
Over-excavation, narrow trenches and irregular sides
Trenches are rarely perfectly straight or square. Soil collapse, hand-dug sections, and machine over-digging all increase volume. Narrow trenches are also harder to pour cleanly, which will inevitably mean more concrete spillage and waste.
Trench bottom condition
Soft or uneven ground may require a blinding layer and/or extra depth for compaction.
Reinforcement displacement
Steel rebar and cages slightly reduce the concrete volume but are usually ignored and accounted for through waste allowance.
Given these considerations, we recommend adding 5-10% to the calculated volume.
When calculating your concrete needs for slabs and square footings, we recommend you take into account the following.
Sub-base variation
Inconsistent compaction or settlement may cause slab-base variations and ultimately alter the slab thickness.
Edge thickening
Slabs often have thickened edges or beams that need to be calculated separately.
Formwork bowing or leakage
Formwork bowing or leaking is especially prevalent with timber formwork, where wet concrete can push the formwork sides outward.
Surface finishing requirements
Power-floating or screeding may require a slightly higher pour level.
Cut-outs & penetrations
Drains, services, or sleeves reduce volume, but these are often offset by waste.
Based on these considerations, we recommend adding 5% for well-formed slabs and up to 10% for larger pours.
Calculating concrete for columns and round footings can be challenging. This is mainly due to using geometric formulas and the difficulty of getting precise excavations on site. There is also a high chance of waste or spillage. With this in mind, we recommend you take the following precautions.
Circular geometry losses
Consider the loss of material from circular holes, since they are often not perfect cylinders and their edges tend to collapse.
Vertical formwork movement
Forms can shift or bulge during pouring, increasing the volume.
Concrete compaction
Vibration causes concrete to settle, sometimes requiring topping up.
Height variations
Column tops are often trimmed later, which requires additional concrete to be poured.
Reinforcement congestion
Tight steel cages reduce placement efficiency, increasing waste.
Given these considerations, it is highly advisable to increase the calculated volume by an additional 7-12%, particularly for in-ground round footings.
Content
Calculating the volume of liquid screed is challenging due to variable floor depths, high flowability, and site-specific conditions. Unlike structural concrete, which is poured into fixed formwork, liquid screed behaves like a liquid, self-levels, and is sensitive to substrate unevenness.
Floor flatness tolerance
Liquid screed flows to the lowest point, which means uneven substrates will significantly increase volume.
Minimum cover depth
Pipes (UFH) and cables dictate screed thickness, often resulting in a thicker screed than planned.
Shrinkage and drying loss
Some liquid screeds shrink slightly and may need topping up.
Perimeter leakage
Poor edge sealing allows screed to escape under walls or insulation.
Primer absorption
Porous substrates absorb part of the mix.
Based on these considerations, we recommend adding 10-15% of concrete to the calculated volume, especially on renovation projects.
Info + FAQ's
Concrete
Concrete is the backbone of modern construction, a versatile material that brings strength and durability to countless structures we see every day. Made from a blend of coarse aggregates, sand, gravel, crushed stone, and even slag, and bound together by cement, which acts as the crucial adhesive, hardening over time to form a solid mass.
One of the fascinating aspects of concrete is its curing process, which is vital for achieving optimal strength. After the concrete is poured and shaped, it begins to cure slowly, often taking about 4 weeks to reach more than 90% of its final strength, with continued improvement possible for up to 3 years. To support this process, it’s essential to keep the concrete damp. You might be surprised to learn that techniques such as applying moisture-retaining compounds or submerging the concrete in water can significantly enhance its early strength and longevity.
Understanding these characteristics and processes not only boosts the performance of your concrete but also ensures that your structures stand the test of time.
Where Can I Buy Concrete?
As a leading supplier of volumetric concrete, we offer a service in which our volumetric concrete trucks deliver directly to your site. We mix the concrete on-site by volume rather than weight, allowing us to scale and mix according to your specific requirements with zero waste. When multiple concrete mixes are required, we can manage combination mixtures to achieve the desired ratios and volumes on the day of delivery.
With our volumetric concrete service, you only pay for what you actually use. This not only maximises your resources but also ensures that any unmixed products remain usable indefinitely. By eliminating waste, you save money and make an eco-friendly choice for your project.
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