Free Concrete Ballast, Sand & Cement Estimator – Updated 2026 Prices
Ballast — also called all-in aggregate, all-in ballast, or combined aggregate — is a mixture of sharp sand and gravel used as the aggregate component in site-mixed concrete. A standard UK ballast typically contains a blend of approximately 60–65% coarse gravel (10–20mm crushed stone or rounded gravel) and 35–40% sharp sand, giving a well-graded aggregate that produces workable, strong concrete when mixed with cement and water. It is one of the most widely used construction materials in the UK for domestic and light commercial projects where ready-mix concrete delivery is not practical or cost-effective.
Understanding how much ballast you need for a concrete project — and how to combine it correctly with cement and water to achieve the required strength — is essential for any UK self-builder, groundworker, or DIYer. Our ballast calculator UK 2026 has been updated to reflect current aggregate and cement prices from major UK builders' merchants and calculates ballast, sharp sand, cement bags, and total material costs for the most common concrete mix ratios used in UK construction, from GEN 1 blinding concrete through to RC30 structural mixes.
Ballast is sold in the UK by the tonne or in 25kg/bulk bags. A bulk bag (approximately 850–1,000kg) is the most cost-effective way to purchase ballast for medium-sized domestic projects such as a shed base, patio, or foundation section. For larger projects — driveways, full house foundations, or commercial slabs — ordering ballast loose by the tonne from a local aggregate supplier or builders' merchant is generally cheaper per tonne and avoids the bag surcharge.
Ballast concrete is used across a wide range of domestic and light commercial construction applications in the UK. Its primary use is in strip and trench fill foundations for house extensions, new builds, outbuildings, and garden walls, where a GEN 3 (1:2:4) or stronger mix is poured into excavated trenches to form the structural base of the building. A typical domestic strip foundation is 600mm wide and 200–300mm deep, and a single trench run of 5–6 metres can require 0.5–0.9 m³ of concrete — roughly 1.0–1.8 tonnes of ballast.
Ground-bearing concrete slabs for shed bases, garages, extensions, and garden studios are another major application for ballast concrete in the UK. These are typically 100–150mm thick and reinforced with A142 or A193 mesh. A 4m × 3m × 0.1m shed base requires approximately 1.2 m³ of concrete — around 1.8 tonnes of ballast and 12–13 bags of cement at a GEN 3 mix. Driveways and paths use a slightly richer mix (RC25 or stronger) to withstand vehicle loading, while fence and gate post holes are typically filled with a rapid-set concrete or a GEN 1 mix.
The mix ratio determines the proportions of cement, fine aggregate (sand), and coarse aggregate (gravel/ballast) in the concrete. In UK practice, concrete mixes are described by designed mix designation (C20/25, C25/30, etc.) for engineered structural applications, or by standardised (GEN/RC) prescriptive mix ratios for routine domestic work. When mixing on site using ballast, the following ratios are most commonly used:
When using pre-mixed ballast (all-in aggregate) rather than separate sand and gravel, the effective ratio is based on the combined aggregate volume. The standard rule of thumb for a GEN 3 mix using all-in ballast is 6 parts ballast to 1 part cement by volume, which is the most widely quoted domestic concrete ratio in the UK. This is a simplified version of the 1:2:4 (cement:sand:coarse aggregate) mix where the sand and gravel are pre-blended in the ballast.
The starting point for any ballast calculation is determining the volume of concrete required in cubic metres: multiply the length × width × depth of the pour. From this volume, you can calculate the quantities of ballast and cement required using the mix ratio. For a GEN 3 mix (6:1 ballast:cement by volume), each cubic metre of finished concrete requires approximately 1,750 kg of all-in ballast and 300 kg of cement (12 × 25kg bags). A water:cement ratio of approximately 0.5 is also required — around 150 litres of water per m³.
It is important to remember that the volume of mixed concrete will be less than the sum of the dry ingredient volumes due to the way aggregate particles pack together and the cement fills the voids. As a rule of thumb, mixing 1 part cement + 6 parts ballast by volume produces approximately 0.7 m³ of finished concrete per m³ of dry materials. Always add a wastage factor — 10% is standard — to account for spillage, uneven ground, and the difficulty of achieving exactly the right depth across large areas.
Buy ballast and aggregates online UK 2026: Travis Perkins | Jewson | Builder Depot | Aggregate Industries UK
Ballast (all-in aggregate) is a pre-blended combination of sharp sand (fine aggregate) and gravel or crushed stone (coarse aggregate). It is the convenient ready-mixed aggregate for concrete production where separate batching of sand and stone is not required. Sharp sand (also called concreting sand or grit sand) is a coarser, angular sand used in concrete mixes and as the fine aggregate component. It differs from soft (building) sand, which is finer and smoother and used in mortar but not concrete. Gravel or stone aggregate (10mm or 20mm) is the coarse component, providing bulk strength and particle interlock in the concrete matrix.
For small domestic pours — shed bases, footings, post holes — using pre-blended ballast is convenient and avoids the need to proportion two separate aggregate materials on site. For larger pours where precise mix control is important, specifying separate sharp sand and 20mm gravel allows the mix designer to optimise the sand/gravel ratio for workability and strength. Most ready-mix concrete suppliers can also supply site-mixed concrete to a designed specification if you provide sufficient notice and order volumes of 0.5 m³ or more.
The price of ballast UK 2026 depends on the quantity ordered, the supplier, and the delivery method. Bulk bags (approximately 850–1,000 kg) typically cost £48–£68 per bag (ex-VAT), including delivery from major online builders' merchants. Loose tonne loads delivered by tipper lorry are generally more economical for larger orders, at approximately £35–£55 per tonne delivered depending on location, with prices in London and the South East typically 10–20% above the national average. Sharp sand and 20mm gravel are priced similarly. Cement (OPC, 25kg bags) costs approximately £7.50–£9.50 per 25kg bag in 2026.
The table below provides ready-reckoner quantities of ballast, sharp sand, and cement required per cubic metre of finished concrete for the four most common UK site-mixed concrete specifications. All quantities include a standard mix yield factor and are based on dry loose volumes converted to weights.
| Mix | Ratio (C:S:G) | All-in Ballast / m³ | Cement / m³ | Cement Bags (25kg) | Water / m³ | Typical Use |
|---|---|---|---|---|---|---|
| GEN 1 | 1:3:6 | ~1,920 kg | ~220 kg | ~9 bags | ~110 litres | Blinding, path bases, non-structural fill |
| GEN 3 | 1:2:4 | ~1,750 kg | ~300 kg | ~12 bags | ~150 litres | Foundations, ground-bearing slabs, paths |
| RC25 | 1:1.5:3 | ~1,650 kg | ~370 kg | ~15 bags | ~185 litres | Reinforced slabs, driveways, garage floors |
| RC30 | 1:1:2 | ~1,500 kg | ~480 kg | ~19 bags | ~240 litres | Heavy-duty structural, heavily loaded slabs |
These quantities are approximate and assume a standard water:cement ratio of 0.5 and normal-weight aggregates with a dry loose bulk density of approximately 1,600 kg/m³ for ballast. Actual quantities may vary slightly depending on aggregate grading, moisture content, and site conditions. Always add 10% wastage to your calculated quantities before ordering.
The table below summarises typical 2026 UK prices for ballast, sharp sand, gravel, and cement from major builders' merchants and aggregate suppliers. All prices are exclusive of VAT. Prices in London and the South East are typically 10–20% higher than the national averages shown.
| Material | Bulk Bag (~850kg) | Loose per Tonne (delivered) | 25kg Bag | Notes |
|---|---|---|---|---|
| All-in Ballast (10mm / 20mm) | £48–£68 | £35–£55/t | £3.50–£5.00 | Most cost-effective in bulk for large pours |
| Sharp Sand (concreting sand) | £44–£62 | £32–£50/t | £3.00–£4.50 | Used in concrete and floor screeds |
| 20mm Gravel / Crushed Stone | £50–£72 | £38–£58/t | £3.50–£5.50 | Coarse aggregate for concrete or drainage |
| 10mm Pea Gravel | £52–£72 | £40–£60/t | £3.50–£5.50 | Drainage, paths, post holes |
| MOT Type 1 Sub-base | £45–£65 | £30–£48/t | £3.00–£4.50 | Sub-base under slabs and driveways |
| Ordinary Portland Cement (OPC) | N/A | N/A | £7.50–£9.50 | 25kg bags; always store dry |
| Ready-Mix Concrete (GEN 3, delivered) | N/A | £95–£135/m³ | N/A | Min order typically 0.5–1.0 m³; plant charge may apply |
Professional Resources 2026: Aggregate Industries UK | Breedon Aggregates UK | Hanson UK Ready-Mix Concrete | Travis Perkins Aggregates
The table below provides recommended concrete specifications for the most common domestic and light commercial applications using site-mixed ballast concrete in the UK. Always consult a structural engineer for any load-bearing or structural element.
| Application | Recommended Mix | Min Depth | Sub-base | Reinforcement | Notes |
|---|---|---|---|---|---|
| Blinding / levelling layer | GEN 1 | 50–75mm | Compacted ground | None | Under foundations or slabs |
| Strip / trench fill foundation | GEN 3 | 200–300mm | Firm undisturbed ground | None (or as engineered) | Building control inspection required |
| Shed / greenhouse base | GEN 3 | 100mm | 100mm MOT Type 1 | Optional A142 | Include DPM under slab |
| Garden patio slab | GEN 3 | 100mm | 100–150mm MOT Type 1 | Optional A142 | Fall away from building |
| Domestic driveway | RC25 | 125–150mm | 150mm MOT Type 1 | A142 or A193 | Cars and light vans only |
| Garage floor (domestic) | RC25 | 125–150mm | 150mm MOT Type 1 + DPM | A193 | Power-float for smooth finish |
| Garden / boundary wall footing | GEN 3 | 200mm | Firm subsoil | None | Width = 3× wall thickness |
| Fence / gate post hole | GEN 1 or rapid-set | 600mm deep | N/A | None | Fill around post; slope top to drain |
| Concrete steps / kerbs | RC25 | 150mm | 100mm hardcore | None or A142 | Shutter and vibrate carefully |
Ballast (all-in aggregate) is a pre-blended mix of sharp sand and gravel or crushed stone. The standard UK composition is approximately 65% coarse aggregate and 35% sharp sand by weight, ready to mix with cement and water.
For a GEN 3 domestic mix using all-in ballast: use 6 parts ballast to 1 part cement by volume. This is the most quoted domestic concrete ratio in the UK and is suitable for most foundations and ground-bearing slabs.
A GEN 3 mix requires approximately 1,750 kg of all-in ballast per cubic metre of finished concrete, plus approximately 300 kg (12 × 25kg bags) of Ordinary Portland Cement.
A standard bulk bag of ballast weighs approximately 850–1,000 kg. For a GEN 3 mix, one bulk bag provides enough ballast for approximately 0.5 m³ of finished concrete.
Ballast costs approximately £48–£68 per bulk bag or £35–£55 per loose tonne delivered (ex-VAT) across the UK in 2026, with London and the South East at the upper end of this range.
The ideal water:cement ratio for site-mixed concrete is approximately 0.5 (50 litres of water per 100 kg of cement). Too much water weakens the concrete — the mix should be workable but not sloppy or pourable.
For pours over 1.0 m³, ready-mix concrete delivered by truck is often more cost-effective and consistent than site-mixing. In 2026, GEN 3 ready-mix costs approximately £95–£135 per m³ delivered.
Always add at least 10% to your calculated volume before ordering. Concrete is difficult to top up once a pour has started, and running out mid-pour can cause a cold joint — a weak plane in the finished slab.
Only sharp sand (coarse, angular grit sand) should be used in concrete. Soft (building) sand is too fine and smooth — using it in concrete significantly reduces strength and increases shrinkage cracking.
Concrete achieves approximately 70% of its final strength at 7 days and reaches its design strength at 28 days. Keep newly poured concrete moist and above 5°C for at least 3–7 days to ensure proper curing.
Do not pour concrete when temperatures are forecast to drop below 2°C within 24 hours. Frost prevents proper curing and can permanently weaken the finished concrete. Use frost blankets if unavoidable.
A standard 140-litre electric cement mixer produces approximately 0.1 m³ of mixed concrete per batch. A 1.2 m³ shed base would therefore require approximately 12–13 mixer loads at a GEN 3 mix.
Concrete work forming part of a building's structure — including foundations, ground floor slabs, and retaining walls — must comply with the Building Regulations 2010 (as amended) and the relevant Approved Documents. The most relevant sections for ballast concrete work in UK domestic construction are Part A (Structure), Part C (Site Preparation), and Part L (Energy Efficiency for habitable floors).
Approved Document A requires that foundations be designed to safely transmit all loads from the building to the ground without causing settlement or movement that would impair the structure or finishes. For domestic buildings up to three storeys, the simplified rules in Approved Document A (Table 10) provide minimum foundation widths and depths based on the load-bearing capacity of different ground types. Building Control inspection at foundation level is required before concrete is poured — do not backfill or cover foundations without obtaining the inspector's sign-off. All concrete used in foundations must comply with BS 8500 for the relevant exposure class.
Approved Document C requires that ground-bearing concrete floor slabs include a continuous damp-proof membrane (DPM) — typically 1200-gauge polythene — to resist the upward passage of ground moisture. The DPM should be laid over the compacted hardcore sub-base and lapped with the damp-proof course (DPC) in the surrounding walls. Where the ground contains contaminants, radon, or other ground gases, additional protective measures may be required under Part C before any concrete is placed.
Official Regulatory Resources: GOV.UK Approved Documents A & C | Planning Portal UK | The Concrete Centre UK | NHBC Standards 2026
For a standard GEN 3 mix (1:2:4) — the most common domestic concrete specification in the UK — you need approximately 1,750 kg of all-in ballast per cubic metre of finished concrete, along with approximately 300 kg (12 × 25kg bags) of Ordinary Portland Cement and around 150 litres of water. For a GEN 1 blinding mix, you need approximately 1,920 kg of ballast and 220 kg of cement per m³. For a stronger RC25 mix (driveways, reinforced slabs), expect approximately 1,650 kg of ballast and 370 kg of cement per m³. Our calculator computes these quantities automatically for your chosen mix ratio and volume.
The most common domestic concrete mix ratio in the UK using all-in ballast is 6 parts ballast to 1 part cement by volume — equivalent to a GEN 3 or C20 mix. For stronger work such as driveways and reinforced slabs, use a 4:1 ballast to cement ratio (equivalent to RC25). For heavy-duty structural work, a 3:1 ratio (RC30) may be specified. Always use sharp sand-based ballast (not soft sand), measure by volume using a consistent container, and use approximately half the cement volume in water. Never add too much water — a wet, sloppy mix is significantly weaker than a stiff, workable mix.
For a typical 4m × 3m × 0.1m (100mm deep) shed base in GEN 3 concrete: volume = 4 × 3 × 0.1 = 1.2 m³. Adding 10% wastage gives 1.32 m³. At 1,750 kg of ballast per m³, you need approximately 2,310 kg of ballast — that is 3 bulk bags (at ~850 kg each, this gives 2,550 kg, leaving a small surplus). You would also need approximately 14 bags of 25kg cement. Our calculator above will compute all these figures automatically if you enter your slab dimensions.
Ballast (all-in aggregate) is a pre-blended mixture of sharp sand (fine aggregate) and gravel or crushed stone (coarse aggregate), typically in a ratio of approximately 35:65 by weight. It is used as the combined aggregate in concrete production. Sharp sand (also called concreting sand or grit sand) is the fine aggregate component only — it is coarser and more angular than soft (building) sand and is used in concrete and floor screeds. When using ballast, you generally do not need to add separate sharp sand — the ballast already contains the fine aggregate fraction. If a mix design calls for separate sand and coarse aggregate, specify sharp sand (not soft sand) for the fine fraction.
In 2026, all-in ballast costs approximately £48–£68 per bulk bag (approximately 850–1,000 kg, ex-VAT) from UK builders' merchants, or £35–£55 per tonne delivered loose by tipper lorry. Prices in London and the South East are typically 10–20% higher. For a 1.2 m³ shed base requiring approximately 2,310 kg of ballast, expect to pay around £110–£180 for ballast in 3 bulk bags, plus approximately £100–£130 for 14 bags of cement. Always check live prices from your local merchant as aggregate prices can fluctuate with fuel and haulage costs.
For pours below 0.5 m³, site-mixing with ballast and cement is usually more economical and practical. For pours between 0.5 m³ and 1.5 m³, both options are viable — ready-mix avoids the labour of mixing and ensures consistent quality, while site-mixing gives more flexibility on timing. For pours over 1.5 m³, ready-mix delivered by truck is generally more cost-effective, faster, and produces a more consistent result than site-mixing. In 2026, ready-mix GEN 3 concrete costs approximately £95–£135 per m³ delivered, with a minimum order of 0.5–1.0 m³ typically applying and a short-load surcharge for small volumes.
The minimum foundation depth in the UK depends on the soil type and the frost depth. As a general rule under Approved Document A, strip foundations for a single-storey extension on firm ground should be a minimum of 450mm deep from finished ground level to the underside of the foundation (to avoid frost heave) and at least 200–300mm thick depending on the wall width and load. On shrinkable clay soils — common across large parts of England — foundations must typically be 900mm–1m or deeper to avoid seasonal movement. Your Building Control Officer will advise on the required depth for your specific ground conditions.
Add 10% to your calculated volume as a standard wastage allowance for straightforward rectangular pours with accurate formwork. Reduce to 5% only for very precise, shuttered pours where spillage is minimal. Increase to 15% for pours onto uneven ground, circular or irregular shapes, or where the depth is hard to control precisely (such as trench fill foundations in variable ground). Never skimp on the wastage allowance for concrete — running out of concrete mid-pour creates a cold joint, which is a permanent weak plane in the structure and a serious defect that building control will flag.
Site-mixed concrete using OPC (Ordinary Portland Cement) begins to set within 1–2 hours of mixing in normal UK temperatures (10–20°C). It achieves initial hardness (can be walked on carefully) after approximately 24 hours, and reaches approximately 70% of its final design strength at 7 days. Full design strength (28-day strength) is achieved at approximately 28 days. Do not load the concrete structure, apply point loads, or build off a foundation until it has reached adequate strength — typically at least 7 days for lightly loaded domestic work. Keep the concrete moist and protected from frost during the curing period.
A freestanding shed base, patio, or garden path does not typically require Building Regulations approval, though you should check for any planning permission requirements if the hardstanding area is large or if it affects surface water drainage. However, a concrete ground floor slab that forms part of a habitable extension or new building does require Building Regulations approval under Part A (structure), Part C (moisture), and Part L (thermal insulation for heated floors). Your local authority Building Control or an approved inspector must be notified and will inspect the sub-base, DPM, reinforcement, and concrete pour. Do not cover any structural concrete without building control sign-off.
Concrete can be poured in cold weather but requires precautions. Do not pour when temperatures are expected to fall below 2°C within 24 hours of the pour, as frost will prevent proper curing and permanently weaken the concrete. If pouring in cold conditions is unavoidable, use warm (not hot) mixing water, cover the freshly poured concrete with insulating frost blankets or hessian immediately after finishing, and consider using a concrete accelerator or rapid-hardening cement to increase early strength gain. In very cold weather (below 0°C), concrete production should cease entirely unless specialist heated mixing and curing arrangements are in place.
For a domestic concrete slab in the UK, a minimum 100mm layer of compacted MOT Type 1 crushed limestone or granite sub-base is recommended beneath the DPM and concrete. For driveways subject to vehicle loading, increase this to 150mm. For slabs on poor or made-up ground, a 200mm sub-base may be required. The sub-base must be well-compacted using a vibrating plate compactor in 75mm layers — poorly compacted sub-base is a leading cause of concrete slab cracking and settlement. MOT Type 1 sub-base costs approximately £30–£48 per tonne delivered in 2026.
Additional Resources 2026: Aggregates at Travis Perkins | Jewson | Builder Depot | Ready-mix at Hanson UK | Concrete guidance at The Concrete Centre | Building regs at GOV.UK