🪨 Ballast Calculator UK
Calculate ballast aggregate tonnage and volume for any UK construction project — concrete mixes, foundations, driveways, and sub-base work. Instant 2026 results.
Ballast Calculator — Aggregate Tonnage & Volume
Enter your project dimensions and mix details to calculate exact ballast tonnage, volume, and bulk bags required.
Typical: 100mm path · 150mm driveway · 200–300mm foundation sub-base
UK 2026 average: £47–£60/tonne delivered
📦 Quantities
📋 Project Notes
⚠️ Key Reminders
What Is Ballast Aggregate & Why Use the Ballast Calculator?
Ballast is a coarse aggregate mix of sharp sand and gravel (typically 10–20mm stone) used as the main bulk component in concrete. Mixed with cement at a 1:5 ratio (cement:ballast), it produces general-purpose C20–C25 concrete suitable for most domestic UK projects. Using a ballast calculator prevents costly over-ordering and ensures you have enough material to complete the pour without running short. For full technical guidance, refer to BS EN 12620 Aggregates for Concrete ↗.
Standard UK construction ballast weighs 1,750–1,800 kg/m³ (1.75–1.80 t/m³). This means 1 tonne of ballast occupies approximately 0.57 m³. Always confirm density with your supplier as moisture content affects the actual figure.
Foundations & Footings
Ballast mixed at 1:5 with cement produces C20 concrete — suitable for strip and pad foundations for domestic extensions and outbuildings.
Driveways & Slabs
For driveways, use a 1:4 or 1:5 cement:ballast mix at minimum 100mm depth. C25 strength is recommended for vehicle loading.
Sub-Base & Hardcore
MOT Type 1 or scalpings are used as compacted sub-base beneath slabs. Typical depths are 100–150mm for paths and 150–300mm for driveways.
Ballast & Aggregate Density Reference — UK Calculator Data
The ballast calculator uses the densities below to convert volume (m³) to tonnage. These are standard UK industry figures — your supplier may provide a specific density for their material.
| Aggregate / Ballast Type | Density (kg/m³) | 1 Tonne = (m³) | Typical Use |
|---|---|---|---|
| Ballast (Sharp Sand & Gravel) | 1,750 | 0.57 m³ | Concrete mixing |
| MOT Type 1 Sub-base | 1,920 | 0.52 m³ | Driveway sub-base |
| Crushed Limestone | 1,800 | 0.56 m³ | Sub-base, paths |
| Sharp Sand | 1,600 | 0.63 m³ | Bedding, mortar |
| Decorative / General Gravel | 1,620 | 0.62 m³ | Driveways, paths |
| Scalpings / Hardcore | 1,850 | 0.54 m³ | Hardcore fill |
Ballast & Cement Mix Ratios — Concrete Calculator Guide
When using the ballast calculator to mix concrete, the cement:ballast ratio determines the final concrete strength. The figures below show how much ballast and cement you need per m³. For full mix design guidance, see our Concrete Cost per m³ guide.
| Mix Ratio (Cement:Ballast) | Ballast per m³ | Cement (25kg bags) | Concrete Strength | Typical Use |
|---|---|---|---|---|
| 1:4 | 2.0 tonnes | 17 bags | C25 | Driveways, structural slabs |
| 1:5 | 2.0 tonnes | 14 bags | C20 | Foundations, general purpose |
| 1:6 | 2.0 tonnes | 12 bags | C15 | Light paths, blinding |
Ballast calculator results are theoretical net volumes. On-site losses from spillage, uneven sub-base, and handling mean you should always order at least 10% more than your calculated quantity. Enable the wastage toggle in the calculator above.
Depth Guide for Common Ballast Applications
- Garden path (pedestrian only): 75–100mm compacted sub-base + 50mm binding layer
- Domestic driveway (cars): 150mm MOT Type 1 sub-base + 100mm concrete slab
- Driveway (vans/light commercial): 200–250mm sub-base + 150mm reinforced slab
- Strip foundation: 150–300mm concrete depending on load and ground conditions
- Garden shed base: 100mm compacted sub-base + 100mm concrete slab
One standard 850kg bulk bag covers approximately 0.48 m² at 100mm depth or 0.32 m² at 150mm depth. For smaller jobs, 25kg bags are more practical despite a higher unit cost — ideal for volumes under 0.5 m³.
Ballast Calculator FAQs — Aggregate Tonnage & Volume
Everything you need to know about calculating ballast quantities, mix ratios, and aggregate ordering for UK projects.
- Example: 5m × 3m × 0.15m = 2.25 m³
- 2.25 × 1,750 = 3,937 kg = 3.94 tonnes
- With 10% wastage: 4.33 tonnes
- In 850kg bulk bags: 6 bags (always round up)
- 1 tonne of ballast ≈ 0.57 m³
- 1 m³ of ballast ≈ 1.75 tonnes
- 1 bulk bag (850kg) ≈ 0.49 m³
- Wet ballast is heavier — can reach 1,900 kg/m³ after rainfall
- 1:4 mix (C25): 2.0 tonnes ballast + 17 × 25kg cement bags + 190L water
- 1:5 mix (C20): 2.0 tonnes ballast + 14 × 25kg cement bags + 160L water
- 1:6 mix (C15): 2.0 tonnes ballast + 12 × 25kg cement bags + 140L water
- Calculate your total tonnes required (use the ballast calculator above)
- Divide total kg by 850 to get number of bulk bags
- Always round up to the nearest whole bag
- Example: 4.33 tonnes = 4,330 kg ÷ 850 = 5.1 → order 6 bulk bags
- Ballast is a sharp sand and gravel mix (10–20mm) — used as the aggregate component in concrete mixing. Not suitable as a standalone sub-base as it doesn't compact stably without cement.
- MOT Type 1 is crushed stone (up to 40mm) — used as a compacted sub-base beneath driveways, paths, and slabs. It self-binds when compacted. Denser at 1,920 kg/m³.
- Use MOT Type 1 beneath your slab, then ballast mixed with cement for the concrete slab itself.
- MOT Type 1 costs approximately £28–£45/tonne; ballast costs £35–£55/tonne (2026 UK prices).
- Loose tip delivery (per tonne): £47–£60 delivered
- 850kg bulk bag: £55–£80 per bag (includes delivery)
- 25kg small bags: £4.50–£7.50 per bag (c.£180–£300/tonne equivalent)
- London/South East: Add 15–25% to all prices above
- Small bags are 3–5× more expensive per tonne — only use for very small volumes under 0.5 m³
- MOT Type 1 sub-base: minimum 100–150mm compacted for cars; 200–300mm for heavier vehicles
- Concrete slab (ballast mix): minimum 100mm for cars; 150mm for vans or frequent use
- Total construction depth: typically 200–300mm below finished level for a domestic driveway
- Always excavate and remove topsoil/organic material before laying sub-base
- Compact sub-base in 100mm layers with a plate compactor for best results