Concrete Volume
Calculator (m³)
Calculate the exact cubic meters of ready-mix concrete needed for your project. Precision-engineered for laymen and pros alike, instantly factoring in site wastage and edge boards.
Total Ready-Mix to Order
3.15m³
Timber Edge Boards
18.0lin.m
1. What are you pouring?
A flat, wide pour used for sheds, driveways, and patios. Needs wooden boards around all 4 edges to hold the liquid concrete.
2. Geometric Dimensions
3. Site Realities
The earth is never perfectly flat. Uneven ground uses more concrete than the pure math suggests. Add a buffer so you don't run out.
4. Build Materials
Timber Shuttering (Edge Boards)
Wet concrete flows like liquid. Calculate the linear meters of wood needed to build a containing wall around the edges. (Note: This wood sits on the outside. It does not subtract from your concrete volume).
Mathematical Breakdown
Net Geometric Volume
Perfectly flat math
3.00m³
Wastage Buffer
At 5% margin
+0.15m³
Slab vs. Trench: What's the Difference?
Whether you are building a shed base or a brick wall, the shape of the hole determines the math. Here is a plain-English guide to groundworks terminology.
Rectangular Slab
A flat, wide area of concrete poured on top of the ground (or slightly sunken). Used for driveways, patios, and shed bases.
Mold Requirement
Needs wooden boards around all 4 edges to stop the liquid spilling out.
Trench Footing
A deep, narrow hole dug straight into the earth. The concrete is poured directly inside to act as a solid underground foundation for a brick wall or house extension.
Mold Requirement
The dirt acts as the mold. You usually do not need wooden boards.
Circular Base
A perfect circle, commonly used as a structural pad for heavy, round objects like hot tubs or agricultural silos.
Mold Requirement
Requires flexible edging (like hard plastic or thin wood) to bend into a circle.
What is "Timber Shuttering"?
Before it sets, concrete is a heavy, sluggish liquid. If you pour it onto flat ground, it will just spread everywhere.
To give the concrete its shape (like a 5m x 4m rectangle), you have to build a temporary wall around the outside using wooden boards. In construction, this is called shuttering or formwork.
Does wood subtract from the volume?
No. The wooden boards sit on the outside of your measurements. If you want a 5m slab, you place the wood exactly 5m apart. The volume of concrete you order stays exactly the same. Our calculator simply tells you how many linear meters of wood to buy at the hardware store to build the outer box.
Liquid in a Box
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Choosing the Right Mix Grade
The volume determines how much arrives, but the Mix Grade determines its structural strength. In the UK, concrete strength is measured in Newtons after a 28-day curing period.
| Mix Grade | Strength (28 Days) | Typical Use Case |
|---|---|---|
| C15 / Gen 1 | 15 Newton | Non-structural mass fill, backing kerbs. |
| C20 / Gen 3 | 20 Newton | Shed bases, internal floors, walkways. |
| C25 / RC25 | 25 Newton | Driveways, patios, standard trench footings. |
| C30 / RC30 | 30 Newton | Commercial yards, heavy-duty paving. |
Delivery Methods
How the concrete gets from the lorry into your shuttering dictates your manpower requirements.
Straight off the Chute
The cheapest method. The 26-tonne lorry reverses up to the slab and pours directly down a chute. You must have excellent, hardstanding access right next to the pour site.
Concrete Pump Hire
Essential for restricted access (like rear gardens). Requires booking a separate line-pump. It adds £300-£500 to the cost but saves massive manual labor.
Barrowing
The lorry drops the mix directly into your wheelbarrows. Only viable for small volumes (under 2m³). 1m³ equals roughly 20-25 heavy wheelbarrow trips.
Ultimate Concrete FAQ
Answers to the most common site questions.