Getting the right amount of concrete for your project is crucial for both cost and success. Order too little and you face costly emergency top-ups; order too much and you pay for material that ends up in a skip. Our concrete calculator is built around UK construction standards — and this guide explains exactly how to use it.
Need a quick estimate? Jump straight to our free concrete calculator tool.
Why Use a UK-Specific Concrete Calculator?
Generic calculators use metric assumptions that don't always match UK building standards. Our calculator is built around:
- UK measurements: metres and UK concrete grade standards (BS 8500 designated and designed mixes)
- Multiple project types: pre-configured for slabs, footings, driveways, and more
- Waste allowance: includes recommended percentages automatically
- Delivery planning: calculates how many truck loads you'll need
- Bag calculator: estimates dry mix bags for smaller projects
Pro tip from Procon 24/7: Always add 5–10% waste allowance to your concrete order. It accounts for ground level variations, spillage, and prevents running short mid-pour. An emergency top-up costs far more than ordering slightly extra upfront.
How to Calculate Concrete Volume: The Basic Formula
Concrete volume in cubic metres (m³) is calculated as:
Volume (m³) = Length (m) × Width (m) × Depth (m)
Example: a 4m × 3m slab at 150mm (0.15m) depth needs 4 × 3 × 0.15 = 1.8m³ of concrete. Add 10% waste allowance and order 2.0m³.
For irregular shapes, split the area into rectangles, calculate each separately, then add the totals.
How to Use the Concrete Calculator: Step-by-Step
Step 1: Select Your Project Type
Each project type has different depth and strength requirements:
- Concrete slab: house extensions, garage floors, workshop bases
- Footings: foundation footings, fence post bases
- Driveway: vehicle access, parking areas
- Garden path: walkways, garden access routes
- Patio: outdoor living spaces, entertaining areas
- Steps: entrance steps, garden terracing
Step 2: Measure Your Area Accurately
- Length and width: measure in metres to the nearest 10cm
- Depth: most projects need 100–200mm (0.10–0.20m)
- Complex shapes: break irregular areas into rectangles and calculate separately
Step 3: Add Your Waste Allowance
We recommend adding extra to account for: ground level variations, spillage during pouring, slightly thicker areas for structural strength, and measurement inaccuracies.
These calculations are estimates based on standard concrete density (2,400 kg/m³). For structural projects or unusual conditions, consult our technical team for precise calculations.
UK Concrete Thickness Guidelines by Project Type
The depth of concrete you need depends on your intended use:
| Project Type | Minimum | Recommended | Notes |
|---|---|---|---|
| Garden paths | 75mm | 100mm | Light foot traffic only |
| Patios | 100mm | 125mm | Standard domestic use |
| Driveways (cars) | 125mm | 150mm | Regular car use |
| Driveways (vans/HGVs) | 150mm | 200mm | Commercial vehicles |
| House slabs | 150mm | 200mm | Structural requirements |
| Strip footings | 200mm | 250mm | As per building regs |
Which Concrete Grade Do You Need for Your Project?
At Procon 24/7, we supply various concrete grades to suit every application. UK concrete is specified under BS 8500 using either designated mixes (GEN, RC, PAV) or designed mixes (C20, C25, C30, etc.):
Standard Grades
- C20/25 (Gen 3): General purpose — paths, non-structural domestic use. Suitable for domestic concrete projects with light loading.
- C25/30 (Gen 4): Driveways, patios, garage floors
- C30/37 (Gen 5): Structural work, house slabs, heavy-duty applications
- C35/45: Commercial and industrial concrete applications
Specialist Mixes
- Fast-set concrete: 6-hour set time for urgent repairs or time-sensitive projects
- Fibre-reinforced concrete: Steel fibres added for crack resistance and improved tensile strength
- Self-compacting: Flows easily around reinforcement bars without vibration
- Waterproof concrete: For basements and retaining walls
Not sure which grade you need? Our team will advise on the best mix for your project. Call us or use the calculator and we'll confirm your grade at the quote stage.
What Affects the Cost of a UK Concrete Project?
Concrete Material Costs (2025 UK Prices)
- C20/25: from £90/m³ — non-structural domestic use
- C25/30: from £100/m³ — driveways, patios, garage slabs
- C30/37: from £110/m³ — structural slabs and footings
- C40/50: from £130/m³ — high-specification structural work
- Small load surcharge: typically £100–£200 for ready-mix orders under 3m³ (no surcharge on volumetric orders)
See our full concrete cost per cubic metre guide for a complete breakdown of delivery charges, part-load fees, and pumping costs.
Delivery and Access Considerations
- Standard delivery: typically included for accessible sites within normal range
- Distance charges: may apply for rural or remote locations beyond 15–20 miles
- Pump charges: available on request via our line pump or boom pump service
- Waiting time: fairly priced for unavoidable site delays
Additional Project Costs to Budget For
- Site preparation and sub-base materials
- Steel reinforcement (mesh or rebar) or fibre-reinforced concrete as an alternative
- Formwork and shuttering
- Labour for laying, finishing, and curing
- Tools and equipment hire
How to Plan Your Concrete Delivery for a Smooth Pour
Before Ordering
- Check access: Confirm concrete trucks can reach your site. If not, ask us about boom pump hire for hard-to-reach pours.
- Prepare the base: Level, compact, and add hardcore if required.
- Set up formwork: Install edging boards and check levels.
- Order reinforcement: Steel mesh or rebar as required by your building plans.
- Gather tools and helpers: Floats, screeds, wheelbarrows, and enough hands.
On Delivery Day
- Be ready: Concrete sets quickly once delivered — no waiting.
- Check the mix: Verify grade and volume against your order confirmation.
- Pour systematically: Start at one end and work across consistently.
- Level and float: Remove air bubbles and smooth the surface promptly.
- Cure properly: Keep moist for a minimum of 7 days.
Ready-mix concrete typically remains workable for 90 minutes from batching — this is the discharge limit set by BS EN 206. Have everything prepared before delivery arrives. If your project is time-critical or site delays are likely, ask us about volumetric concrete — mixed fresh on-site, giving you a full working window from the moment of mixing.
Procon 24/7 covers Yorkshire and the North West with same-day delivery. Call to confirm your delivery slot and access requirements before ordering.
Frequently Asked Questions About Concrete Calculators
How accurate is a concrete calculator?
Our calculator is accurate to within 5% for standard rectangular areas. For complex shapes or critical structural work, we recommend contacting our technical team for precise calculations based on your actual dimensions.
Can I use the calculator for commercial projects?
Yes — but commercial projects often have specific requirements for grade, reinforcement, and Building Regulations compliance. Contact our commercial concrete team for detailed technical specifications.
What if I order too much concrete?
Excess concrete can sometimes be used for garden features, repair work, or future projects. However, it's better to order slightly short and arrange a top-up delivery than to pay for significant overordering.
Where does Procon 24/7 deliver?
We deliver across Yorkshire — including Sheffield, Leeds, Bradford, Harrogate, Wakefield, and Barnsley — and across the North West, including Manchester and surrounding areas. Same-day delivery is available.
What payment methods do you accept?
Cash on delivery, company accounts, and most major credit and debit cards. Payment terms are available for established commercial customers.
What's the difference between ready-mix and volumetric concrete?
Ready-mix concrete is batched at the plant and delivered to site. Volumetric concrete is mixed fresh on your site from a mobile batching unit — you only pay for what you use, with no time pressure on the pour.
Will a part-load surcharge apply to my order?
Ready-mix suppliers typically apply a short-load surcharge — often £100–£200 — for orders under 3m³, because the truck runs partially empty. If your calculator result is under 3m³, ask about volumetric concrete instead: you pay only for what is mixed, with no minimum order and no surcharge.
How do I convert cubic metres to the number of concrete bags needed?
One cubic metre of concrete weighs approximately 2,400 kg. That equates to around 96 bags of 25 kg premix or 120 bags of 20 kg. For anything above 0.5m³, professional delivery is usually cheaper than buying bags once you factor in bag cost, mixer hire, and labour.
What is the difference between designated mixes like GEN 3 and designed mixes like C25/30?
Designated mixes (GEN 0–4, RC 25–50, PAV 1–2) are pre-defined in BS 8500 for common applications and are specified by name. Designed mixes like C25/30 specify the characteristic compressive strength directly, giving the engineer control over exact performance. For domestic projects a designated mix is usually sufficient; structural work often requires a designed mix.
