Sub-Base Calculator
UK Guidelines:
- Use Type 1 MOT (1800 kg/m³) for driveways and paths
- 75–100mm for paths, 100–150mm for driveways, 225mm for roads
- Compaction: 98% of maximum dry density recommended
USA Guidelines:
- Use compacted crushed stone or gravel
- Thickness varies by traffic load and soil quality
- Follow AASHTO/ASTM standards for grading and certification
- Use Type 1 MOT (1800 kg/m³) for driveways and paths
- 75–100mm for paths, 100–150mm for driveways, 225mm for roads
- Compaction: 98% of maximum dry density recommended
USA Guidelines:
- Use compacted crushed stone or gravel
- Thickness varies by traffic load and soil quality
- Follow AASHTO/ASTM standards for grading and certification
Results:
Volume: m³
Weight: tonnes
Sub-Base Calculator & DIY Ground Prep Guide
Need to build a patio, driveway, or garden path? This calculator helps you estimate how much sub-base you’ll need. Whether you’re using MOT Type 1 in the UK or gravel base in the USA, this tool is perfect for DIYers, landscapers, contractors, and builders who want accuracy and simplicity.
Use this paving material estimator to calculate sub-base volume and weight based on area, depth, and material type. Ideal for those needing to calculate MOT Type 1 sub-base or plan their base before pouring ready-mix concrete.
📏 Sub-Base Depth & Specification
- 🇬🇧 UK Paths: 75–100mm MOT Type 1
- 🇬🇧 UK Driveways: 100–150mm MOT Type 1
- 🇺🇸 USA Light Duty: 4 inches compacted gravel
- 🇺🇸 USA Heavy Duty: 6–8 inches or more depending on soil
- Add 10% waste margin for trimming and compaction
📊 Material Densities & Volume Conversions
| Material | Density (kg/m³) | Density (lb/ft³) |
|---|---|---|
| Type 1 MOT (UK) | 1800 | 112 |
| Type 2 MOT (UK) | 1820 | 114 |
| Crushed Stone (USA) | 1600 | 100 |
| Gravel Base (USA) | 1700 | 106 |
✅ Pro Tips
- Compact in layers no deeper than 50mm
- Use a vibrating plate for best compaction
- Allow for drainage with a slight slope (1:60)
- Always measure twice – then order
- Avoid pouring concrete during frost conditions
❌ Mistakes to Avoid
- Skipping compaction
- Wrong depth for load type
- Using sand instead of gravel as base
- Not checking finished height including pavers
💬 FAQs
- Q: How much MOT Type 1 do I need for 10m² at 100mm?
A: You’ll need 1m³ or roughly 1.8 tonnes. - Q: What’s the standard base for a driveway?
A: 100–150mm compacted MOT Type 1 or crushed gravel. - Q: Can I use sand instead of MOT Type 1?
A: No – sand lacks structural strength needed for load-bearing layers.
