UK Concrete Volume Calculator
Use this free concrete calculator UK tool to estimate how much concrete you need in cubic metres, litres, and bags. Choose your project type, enter dimensions, and click calculate.
Enter length, width, depth and quantity for your slab/base.
How this concrete calculator UK works
In the UK, ready-mix concrete is normally ordered in cubic metres (m³). This calculator converts your dimensions into volume and then applies a waste allowance so you can place a practical order, not just a theoretical one.
The tool supports the most common jobs:
- Slabs and shed bases (length × width × depth)
- Footings and trenches (length × width × depth)
- Columns and post holes (cylindrical formula)
Concrete volume formulas
Rectangular concrete sections
For slabs and footings, use:
Volume = Length × Width × Depth × Quantity
All dimensions should be converted to metres first. For example, 100mm depth = 0.1m.
Cylindrical concrete sections
For piers and post holes, use:
Volume = π × (Diameter ÷ 2)² × Depth × Quantity
This is useful for fence posts, pergola supports, and small foundation piers.
Typical thicknesses for UK projects
Always follow building regs and structural advice for your exact job, but these are common starting points used by builders and DIYers:
- Garden path: 75mm to 100mm
- Shed base: 100mm (often reinforced)
- Driveway: 100mm to 150mm depending on load
- House foundation trench: depth and width vary by ground conditions and design
Ready-mix vs bagged concrete in the UK
Ready-mix concrete
Best for larger pours. It saves time, improves consistency, and is usually more practical once your requirement gets beyond a small DIY volume.
Bagged concrete
Good for patch repairs, single post holes, and small jobs. This page also shows a rough bag estimate (20kg and 25kg), so you can compare options quickly.
Worked examples
Example 1: Shed base
A slab measuring 5m × 3m × 0.1m gives:
5 × 3 × 0.1 = 1.5m³. With 10% waste, order about 1.65m³ (rounded up to supplier increments).
Example 2: 8 post holes
Each hole is 300mm diameter and 600mm deep:
Converted to metres: diameter 0.3m, depth 0.6m.
Volume per hole = π × (0.15²) × 0.6 ≈ 0.042m³.
Total for 8 holes ≈ 0.339m³, then add waste allowance.
Tips for ordering concrete in the UK
- Round up your final order to avoid running short during a pour.
- Confirm minimum order quantities and delivery charges with your local supplier.
- Plan access for the mixer truck or pump before delivery day.
- Check weather and ground prep so the pour can happen in one session.
- For structural work, use the specified strength class from your engineer.
FAQ
How much is 1 cubic metre of concrete?
It depends on region, mix type, and delivery conditions. Enter your supplier rate in the calculator to estimate project cost instantly.
Should I add extra concrete for waste?
Yes. A 5% to 10% allowance is common. Uneven sub-base, spillages, and formwork variations can all increase real usage.
Can I use this for foundations?
You can estimate volume, but foundation design should always match structural drawings, ground conditions, and local building control requirements.
Final note
This concrete calculator UK page is designed to help you plan materials quickly and avoid under-ordering. For critical structural jobs, verify dimensions and specifications with a qualified professional before pouring.