Concrete Calculator UK 2026: Volume, Bags, Cost & Mix Guide Free Tool
Accurate concrete calculator UK – estimate cubic metres, ready-mix bags, cement & ballast for slabs, footings, shed bases. Updated for 2026 British building standards, with 1:2:4 mix ratios and real-time cost per m³.
Estimate your concrete needs
Enter project dimensions in metres and mm (depth). We’ll calculate exact volume, number of bags, and separate cement/ballast.
📦 Concrete Volume
🛒 Ready-mix bags (20kg)
💰 Estimated cost (ready-mix)
🧱 Cement (25kg bags)
⛰️ Ballast (tonnes)
Why accurate concrete calculation matters (2026 UK guide)
Whether you're pouring a concrete slab, foundation, shed base or driveway, using a precise concrete calculator UK prevents waste and saves money. In 2026, material costs vary: ready-mix concrete averages £150–£190 per m³, and ordering 10% extra avoids shortfalls. Our tool supports concrete volume calculator, concrete bag calculator and 1:2:4 concrete mix calculator for DIY projects.
For British builders, concrete footing calculator ensures compliance with NHBC standards. Below, we explain how to measure, mix ratios, and estimate ballast/cement using the same formulas trusted by UK tradesmen.
Step-by-step: how to calculate concrete (formula + pro tips)
1. Measure in metres and millimetres
Concrete calculator formula: Length (m) × Width (m) × Depth (m) = cubic metres (m³). Convert depth from mm to metres: divide by 1000. Example: 5m x 3m x 0.1m = 1.5 m³. Add waste (5-10%) for spillage and uneven ground.
2. Choose your mix type
- Ready-mix concrete: delivered by truck – ideal for large volumes, use ready mix concrete calculator price to get quotes.
- DIY bagged concrete: 20kg bags cover ~0.01 m³ each. For 1.5 m³ you'll need ~150 bags.
- Separate cement & ballast (1:2:4 mix): Every m³ requires ~12 x 25kg cement bags + 1.6 tonnes ballast.
| Project type | Typical depth (mm) | Volume per 10m² | Recommended mix |
|---|---|---|---|
| Shed base / Patio slab | 100–125 mm | 1.0–1.25 m³ | C20 (1:2:4) or bagged |
| Driveway (cars) | 150 mm | 1.5 m³ per 10m² | C25/30 reinforced |
| Strip foundation | 250–300 mm | 2.5–3.0 m³ per linear metre (0.3m width) | C25 or GEN3 |
| Concrete footings | min 150mm | varies | ST1 or GEN1 |
Pro insight 2026: With rising aggregate costs, using a concrete aggregate calculator helps reduce waste. Many UK suppliers now offer 'sustainable concrete' with recycled ballast—our tool adapts to standard 1:2:4 for eco-accuracy.
2026 concrete price trends & cost calculator UK
Current price of concrete per m3 calculator shows ready-mix range: £155 – £195 per m³ (including VAT). DIY bagged: 20kg bag = £4.50–£6.50, so 150 bags cost £675–975, but labour intensive. Our built-in concrete cost calculator updates dynamically – just adjust price per m³ field.
For concrete driveway cost calculator uk, add reinforcement (steel mesh) and labour. A typical 30m² driveway costs £2,200–£3,500 in 2026; using this concrete slab calculator uk ensures you order precisely.
Concrete mix calculator: 1:2:4 & ballast breakdown
For DIY, the 1:2:4 mix is UK standard for general use. Our concrete mix calculator above shows cement bags (25kg) and ballast (tonnes). Concrete ballast calculator formula: 1m³ needs approx 1.6–1.8 tonnes ballast. Multiply by your volume, and you'll get accurate skip/tipper quantities.
Quick checklist before pouring concrete (2026)
- ✅ Sub-base compacted: type 1 mot, 75–150mm depth.
- ✅ Formwork secure: timber edges, use spirit level.
- ✅ Reinforcement: A142/A193 mesh for slabs & driveways.
- ✅ Weather check: avoid freezing/rain for 24h.
- ✅ Order with 5-10% waste: apply our waste factor.
Specialist concrete calculators (shed base, footings & lintels)
Our core tool functions as a shed base concrete mix calculator, concrete footing calculator uk and concrete block calculator (by estimating total volume for blockwork fill). Use the same dimensions: length × width × depth, then convert to number of 100mm concrete blocks? For solid fill, our volume data is essential. Concrete lintel size calculator requires structural calculations, but our volume tool helps estimate concrete for custom lintel pours. Always consult structural engineer for heavy loads.
Additionally, cemex concrete calculator and wickes concrete calculator follow similar principles; we provide full transparency with 2026 mix ratios.
Frequently asked questions – concrete calculator UK
Approximately 100 bags (each 20kg bag yields ~0.01m³). For 2m³, you need 200 bags. Use our concrete bag calculator for exact figures.
C20 (1:2:4 mix) or GEN3 concrete, 100mm thickness. Add steel mesh for heavy sheds. Our concrete mix calculator gives you cement/ballast amounts.
Length × width × depth (in metres) = m³. Use our concrete slab calculator uk above; includes waste.
Around £165 per m³, but varies by location. Our concrete price calculator lets you input local rates.
About 1.6 tonnes ballast + 12 bags (25kg) cement. Adjust with our ballast calculator for concrete tool.
Yes – input footing length, width, depth. Use our concrete footing calculator to get volume and reinforcement estimates.