Ready‑Mix Volume | ConcreteMaths.com

Work out how many cubic metres of ready-mix concrete you need for slabs, driveways, garage bases, footings, foundations, oversite pours and small commercial jobs — with waste allowance, truck-load guidance and 2026 UK ordering notes.

Use your measured dimensions in metres. For millimetres, divide by 1,000 first — for example, 100mm depth = 0.10m. The guide gives base volume, recommended order volume with waste, and an approximate number of full truck loads.

2.00m³

2.20m³

Important:Always round up to the supplier’s ordering increment. Many UK suppliers quote in 0.1m³ or 0.5m³ increments, and small volumes may attract a short-load charge. Confirm your final quantity, mix grade, slump and delivery access with your local supplier before booking.

2026 Ordering Tip: Volume Accuracy Matters More Than Ever

UK ready-mix demand has remained under pressure, but delivery costs, fuel costs, waiting-time charges and short-load fees still make over-ordering expensive. A careful cubic-metre estimate helps you avoid both problems: running short during a pour and paying for concrete you do not need.

Ready-Mix Concrete Volume Guide UK 2026 — What This Page Does

The Ready-Mix Concrete Volume Guide helps UK homeowners, builders, groundworkers, landscapers and self-builders estimate how many cubic metres of concrete are needed before placing an order. Ready-mix concrete is normally sold by volume in cubic metres, so even a small measuring mistake can change the cost, the delivery plan and the number of truck loads required. This 2026 guide explains the working, the waste allowance, the right way to measure depth, and the practical ordering checks you should complete before a lorry arrives on site.

The basic formula is simple: length × width × depth = concrete volume in m³. The difficult part is making sure every measurement uses metres, that the depth reflects the actual finished concrete thickness, and that you add an allowance for uneven ground, spillage, formwork movement, trench irregularity and normal site tolerances. A perfectly square, well-prepared slab may only need a small extra allowance. A hand-dug trench, old driveway, garden base or extension foundation may need more because excavations are rarely as neat as the drawing suggests.

This page is built for practical UK use. It supports common domestic and light commercial pours including shed bases, patio slabs, driveways, garage floors, oversite concrete, strip footings, trench fill foundations, kerb backing, fence post pads, hot tub bases and garden room slabs. For structural concrete, the volume working is only the first step. You should also choose the correct concrete grade, exposure class, reinforcement design, cover, compaction and curing method. For that next step, use theMix Strength Guideand theBS 8500 Mix Design Reference Guide.

Why cubic metres matter when ordering ready-mix

Ready-mix concrete is batched at a plant or produced by a volumetric mixer and delivered to site as a measured quantity. If you under-order, the pour can stop before the slab or trench is complete. That can create cold joints, delays, extra call-out costs and a weaker-looking finish. If you over-order, you may need to pay disposal costs or find somewhere safe and legal to place excess concrete. In 2026, with suppliers still watching costs and delivery efficiency closely, accurate measurement is one of the easiest ways to keep a small project under control.

The guide uses an 8m³ reference load for the truck-load estimate because many UK ready-mix projects are planned around 6m³ to 8m³ drum mixer deliveries. Actual capacity varies by supplier, vehicle size, local roads, payload restrictions and site access. A small urban delivery may use a smaller truck. A volumetric concrete service may work out the order differently because the mix is produced on site. Treat the truck-load result as a planning guide, not a replacement for supplier confirmation.

Project Type: Patio or Path Slab; Common Depth: 75–100mm; Volume Example: 10m² × 0.10m = 1.00m³; 2026 Ordering Note: Add 5–10% for edging and level variation
Project Type: Shed or Garden Room Base; Common Depth: 100–150mm; Volume Example: 12m² × 0.125m = 1.50m³; 2026 Ordering Note: Check base specification from supplier/installer
Project Type: Domestic Driveway; Common Depth: 100–150mm; Volume Example: 30m² × 0.125m = 3.75m³; 2026 Ordering Note: Consider reinforcement, sub-base and exposure
Project Type: Garage Floor; Common Depth: 100–150mm; Volume Example: 20m² × 0.15m = 3.00m³; 2026 Ordering Note: Confirm DPM, insulation and finish level first
Project Type: Strip Footing; Common Depth: Width × depth varies; Volume Example: 20m × 0.60m × 0.30m = 3.60m³; 2026 Ordering Note: Hand-dug trenches often need 10–15% waste
Project Type: Trench Fill Foundation; Common Depth: Often deeper; Volume Example: 18m × 0.60m × 0.90m = 9.72m³; 2026 Ordering Note: May need multiple loads or timed deliveries

How to Work out Ready-Mix Concrete Volume Correctly

To work out concrete volume, measure the length, width and depth of the area and convert everything into metres. If your depth is shown in millimetres, divide by 1,000. A 100mm slab depth is 0.10m. A 150mm driveway depth is 0.15m. A 225mm footing depth is 0.225m. Once the units match, multiply the three numbers together. The result is the base volume before waste.

For a rectangular slab, the formula is straightforward. A garage base measuring 6m long, 4m wide and 0.15m deep needs 6 × 4 × 0.15 = 3.60m³ before waste. With 10% extra, the suggested order becomes 3.96m³, which most users would discuss with the supplier as roughly 4.0m³. If the supplier only accepts half-cubic-metre increments, the final order may be rounded to 4.0m³ or 4.5m³ depending on site conditions, access and risk tolerance.

For footings, use the total trench length rather than the footprint of the building. If a foundation trench is 24m long, 0.60m wide and 0.45m deep, the base volume is 24 × 0.60 × 0.45 = 6.48m³. A 10% allowance increases this to about 7.13m³. If the ground is loose, the trench sides are uneven or the bottom varies in level, a 12–15% allowance may be safer. Always check foundation dimensions with your drawings, building control requirements or structural engineer before ordering.

For circular pads or round bases, the volume is area × depth. The area of a circle is π × radius². For example, a circular hot tub base with a diameter of 3m has a radius of 1.5m. The area is approximately 7.07m². At 0.125m deep, the concrete volume is 0.88m³ before waste. With a 10% allowance, the order would be around 0.97m³. Small pours like this often need careful price checking because short-load fees can make ready-mix less economical than site-mixed concrete or a local volumetric supplier.

Recommended waste allowance in 2026

A waste allowance is not simply wasted concrete. It is a planning buffer for real-world site conditions. Even when formwork is neat, some concrete is lost through minor spillage, variations in sub-base level, deeper areas around edges, small hollows and uneven compaction. A 5% allowance may be enough for a carefully formed slab on a well-compacted MOT Type 1 sub-base. A 10% allowance is a common domestic planning figure for slabs, driveways and bases. A 15% allowance is sensible for hand-dug trenches, old excavations, sloping ground, broken edges or projects where running short would be much more costly than ordering a little extra.

In 2026, many UK customers are paying close attention to material costs, delivery charges and concrete waste. However, trying to order the exact mathematical volume with no allowance is risky. Concrete cannot be stretched once the lorry is on site. If the pour stops short, a return delivery may cost far more than the small amount you saved. For structural pours, the quality issue can be more important than the cost issue because interrupted pours may create weak or visible construction joints. The guide therefore shows both base volume and suggested order volume.

Shape / Pour Type: Rectangle / Square; Formula: Length × width × depth; Use For: Slabs, bases, floors, patios, driveways
Shape / Pour Type: Strip Footing; Formula: Total trench length × trench width × concrete depth; Use For: Walls, extensions, retaining walls, garden walls
Shape / Pour Type: Circle; Formula: 3.142 × radius² × depth; Use For: Round pads, tanks, hot tub bases, circular plinths
Shape / Pour Type: Multiple Areas; Formula: Area 1 volume + area 2 volume + area 3 volume; Use For: L-shaped slabs, stepped patios, mixed foundation sections
Shape / Pour Type: Waste Allowance; Formula: Base volume × 1.05, 1.10 or 1.15; Use For: Final ready-mix order planning

2026 UK Ready-Mix Concrete Ordering Context

Ready-mix concrete pricing and availability are affected by the wider construction market, regional demand, plant location, delivery distance, cement and aggregate costs, fuel costs, labour availability and site waiting time. In 2026, UK construction materials data and industry commentary continued to show pressure in the market, with ready-mixed concrete volumes remaining weak in several regions. For users, that does not mean every quote will be cheaper. It often means suppliers are more careful about efficient loads, minimum orders, travel time and cancellation rules.

For small domestic jobs, the biggest cost surprises are usually not caused by the concrete volume itself. They come from short-load charges, pump hire, waiting time, difficult access, weekend delivery, out-of-area delivery or a second lorry needed because the first order was too low. This is why a ready-mix concrete volume guide should be used alongside a delivery cost guide and a practical site checklist. The cheapest quote per m³ may not be the cheapest delivered job if the truck cannot get near the pour or the team is not ready when the lorry arrives.

Typical UK ready-mix prices in 2026 vary widely by region and grade. Many public price guides place standard ready-mix concrete in a broad range around £110–£160 per m³ before project-specific extras, with London and the South East often higher. Some London-focused supplier guidance places standard C25–C30 concrete around £110–£142 per m³ before VAT and delivery, with delivered totals higher when transport and services are included. Treat any online figure as a guide only. Your actual quote depends on the grade, volume, plant distance, additives, fibre reinforcement, pump requirement and booking conditions.

BS 8500, BS EN 206 and volume working

Volume working is not the same as concrete specification. The guide tells you how much concrete you may need. Standards and project design tell you what type of concrete you should order. In the UK, concrete specification is commonly aligned with BS EN 206 and the complementary British Standard BS 8500. BS 8500 is published in two parts: guidance for the specifier and specification for constituent materials and concrete. For normal domestic work, many customers order common prescribed or designated mixes through the supplier. For structural work, exposed driveways, reinforced concrete, aggressive ground or engineer-designed foundations, the mix should be selected by a competent person.

Do not order only by saying “I need 4 cubic metres.” A complete order normally includes volume, grade/designation, slump or workability, delivery method, access notes, discharge method, arrival time and any special requirements such as fibres, admixtures, air entrainment, waterproofing admixture or pump mix. If you are unsure, tell the supplier exactly what you are building, the depth, the reinforcement, the exposure and how you plan to place the concrete. The supplier can then advise what is available, but for structural responsibility you should follow the engineer, designer or building control requirements.

Step-by-Step: Measure Before You Order Ready-Mix Concrete

1. Split the project into simple shapes

Break an L-shaped driveway, stepped patio or foundation layout into rectangles and trenches. Work out each section separately, then add them together. This gives a better result than guessing one average area.

2. Confirm the finished depth

Use the concrete depth, not the total dig depth. If the excavation includes 150mm sub-base and 100mm concrete, the guide depth should be 0.10m, not 0.25m.

3. Convert millimetres to metres

100mm is 0.10m, 125mm is 0.125m, 150mm is 0.15m and 300mm is 0.30m. Most incorrect concrete orders come from mixing up millimetres, centimetres and metres.

4. Add realistic waste allowance

Use 5% for very neat formwork, 10% for typical domestic work and 15% where trenches or excavations are irregular. Ask your contractor if they prefer a different project-specific allowance.

5. Round to supplier increments

Some suppliers quote in 0.1m³ increments, others round differently. A determined volume of 3.96m³ may be ordered as 4.0m³, but check the supplier’s rules before confirming.

6. Plan the delivery and placing method

Confirm whether the concrete can be chute-discharged, barrowed, pumped or placed with a conveyor. The placing method can affect slump, timing, labour and cost.

Worked Examples for Common UK Concrete Projects

Example 1: Shed base concrete volume

A shed base is 4m long, 3m wide and 100mm deep. Convert 100mm to 0.10m. The base volume is 4 × 3 × 0.10 = 1.20m³. With a 10% allowance, the order volume is 1.32m³. Because this is a small ready-mix quantity, ask suppliers about minimum order size and short-load charges. A volumetric mixer may be useful if access is tight or the supplier can produce exactly what is needed on site.

Example 2: Domestic driveway concrete volume

A driveway is 8m long, 3.5m wide and 125mm deep. Convert 125mm to 0.125m. The base volume is 8 × 3.5 × 0.125 = 3.50m³. With a 10% allowance, the suggested order is 3.85m³. For driveways, volume is only part of the decision. You should also consider sub-base quality, reinforcement, joints, surface finish, drainage, frost exposure and whether air-entrained concrete is appropriate for de-icing salt exposure.

Example 3: Garage floor concrete volume

A garage floor measures 6m by 5m and is designed at 150mm deep. The base volume is 6 × 5 × 0.15 = 4.50m³. With 5% waste, the order is 4.73m³. With 10% waste, the order is 4.95m³. For a garage slab, make sure the damp proof membrane, insulation, edge formwork, finished floor level and any thickened edge details are complete before ordering. If the slab includes deeper beams or a separate ramp, work out those volumes separately and add them to the main slab.

Example 4: Strip footing volume

An extension footing has a total trench length of 30m, a trench width of 600mm and a concrete depth of 300mm. Convert width to 0.60m and depth to 0.30m. The base volume is 30 × 0.60 × 0.30 = 5.40m³. With 10% waste, order about 5.94m³. If the trenches are uneven, deeper in corners or widened by loose ground, the real volume may be higher. Measure after excavation, not only from the drawing.

Common Ready-Mix Volume Mistakes to Avoid in 2026

The most common concrete ordering mistake is using the excavation depth instead of the finished concrete depth. A driveway build-up may include a sub-base, sand blinding, membrane, reinforcement and concrete. The guide should only use the concrete thickness. If the whole dig is 250mm deep but the concrete layer is 125mm, enter 0.125m. Entering 0.25m would double the order and could add unnecessary cost, waste and disposal problems.

The second mistake is measuring only one side of an uneven area. Older patios, driveways and garden slabs are rarely perfectly square. Measure at several points and use the largest safe dimensions or split the area into smaller rectangles. For a driveway that tapers from 3.2m wide at one end to 3.8m at the other, use the average width only if the sides are straight and the shape is regular. If the shape is irregular, divide it into rectangles and triangles or ask your contractor to measure from the actual shuttering.

The third mistake is forgetting thickened edges, ramps, steps and pads. A garage slab may be 100mm deep across most of the floor but 300mm deep at a thickened edge. A garden room base may have deeper pads under load points. A driveway may include a deeper apron at the entrance or a ramp into the garage. These extra volumes should be determined separately and added to the main slab volume before waste allowance is applied.

The fourth mistake is not checking whether reinforcement or mesh affects placement. Reinforcement does not usually reduce the concrete volume enough to ignore normal working, but it can affect how easily concrete flows through the area. A congested footing, narrow trench or reinforced slab may need a suitable workability or pump mix. When discussing the order, tell the supplier whether the concrete will be placed by chute, barrow, pump or direct discharge.

The fifth mistake is ordering too late. Ready-mix concrete is time-sensitive, and suppliers may have busy morning slots, distance limits and cancellation rules. In 2026, efficient delivery planning matters because concrete suppliers are managing vehicle use, fuel, driver time and plant scheduling carefully. Book early, but only after the site is ready enough to measure accurately. For footings, many contractors prefer to measure after excavation because trench width and depth can change during digging.

Site Access, Delivery Method and Why It Changes the Final Order

A perfect volume working is only useful if the concrete can reach the pour. Before ordering ready-mix, confirm whether the truck can reverse close enough for chute discharge. A standard chute may only reach a limited distance from the back of the lorry. If the pour is behind a house, down a narrow side path, across a garden, inside a building or over a boundary wall, you may need barrows, a concrete pump, a line pump, a boom pump or a volumetric mixer with extended hoses. The delivery method can affect cost and also the type of mix the supplier recommends.

Barrowing concrete is possible for smaller volumes, but it takes labour and time. If a lorry is waiting while a small team barrows several cubic metres through a narrow access route, waiting-time charges may apply. Pumping adds hire cost, but it can make the pour faster, cleaner and safer for larger volumes or awkward sites. When using a pump, ask whether the mix needs to be pumpable, whether a minimum pump volume applies, and how much extra concrete is needed for priming the pump line. Some pump lines require additional material that should be planned before the lorry arrives.

Access checks should include road width, overhead cables, parked cars, soft ground, low branches, turning space, steep slopes, manhole covers and neighbour access. Concrete lorries are heavy. Do not assume a truck can drive over a driveway, pavement, lawn or weak surface without permission and assessment. If the truck cannot reach the site on the day, the order may be delayed or cancelled, and you may still face charges. Accurate volume planning and delivery planning should happen together.

Also plan washout and leftover concrete. Suppliers cannot usually wash out into drains, gardens or public roads. Have a designated washout area or tub ready, and decide where a small amount of excess concrete can be placed safely. Some users form a small spare pad, stepping stone area or fence post hole in case a little concrete remains. Never plan to dispose of excess concrete in a way that blocks drains, damages soil, affects neighbours or breaches local rules.

Concrete Depth Is Not the Whole Specification

Many people search for a single answer such as “how deep should concrete be?” but the correct answer depends on load, ground conditions, sub-base, reinforcement, exposure and use. A 100mm slab may perform well for a light garden path on a prepared base, but it may be inadequate for heavier vehicle loading or weak ground. A 150mm slab may still fail if the sub-base is poor, joints are wrong, water is trapped, or curing is ignored. The guide estimates volume; it does not replace design.

For patios and paths, the concrete is often part of a wider build-up that includes compacted sub-base and sometimes a decorative finish or paving system. For driveways, drainage, falls, expansion joints, control joints, reinforcement, air entrainment and surface finish may matter. For garages and floors, insulation, damp proof membranes, vapour control layers, finished floor levels and building regulation requirements may determine the final depth. For foundations, building control, soil type, tree influence, frost depth and structural loads can determine width and depth.

When measuring for ready-mix, record three things separately: the excavation depth, the sub-base depth and the concrete depth. This makes the order clearer and helps avoid confusion when speaking to suppliers. For example, “The total dig is 250mm, with 125mm compacted sub-base and 125mm concrete” is much clearer than “It is 250mm deep.” Clear communication reduces the risk of ordering the wrong amount or the wrong specification.

Finally, remember that concrete volume does not include materials such as hardcore, Type 1 sub-base, sand blinding, DPM, insulation, mesh, spacers, shuttering timber, curing compound or sealant. Use the related guides on ConcreteMaths for those quantities. A complete project estimate should include both the concrete order and the supporting materials needed to prepare, place, finish and cure it properly.

Factor: Best Volume Range; Ready-Mix Concrete: 1m³+ where access works; Site-Mixed Concrete: Very small pours and repairs
Factor: Consistency; Ready-Mix Concrete: Batch controlled; Site-Mixed Concrete: Depends on mixing accuracy
Factor: Labour Requirement; Ready-Mix Concrete: Lower mixing labour; Site-Mixed Concrete: Higher manual labour
Factor: Short-Load Risk; Ready-Mix Concrete: Possible below supplier threshold; Site-Mixed Concrete: No lorry minimum
Factor: Speed of Pour; Ready-Mix Concrete: Fast placement; Site-Mixed Concrete: Slower mixing and placing
Factor: Specification Control; Ready-Mix Concrete: Supplier documentation available; Site-Mixed Concrete: Usually not certified

For additional concrete quantity and estimating resources, you can also visit ConcreteCalcs.com.