UK MOT Type 1 calculator
MOT Type 1 Calculator
Enter your area and compacted depth below to estimate an MOT Type 1 order in cubic metres, tonnes, and 850 kg bulk bags. For a quick benchmark, 20 m2 at 100 mm needs about 4.40 tonnes after a 10% allowance.
Quick answer
- 20 m2 at 75 mm depth needs about 1.65 m3 or 3.30 tonnes.
- 20 m2 at 100 mm depth needs about 2.20 m3 or 4.40 tonnes.
- 20 m2 at 150 mm depth needs about 3.30 m3 or 6.60 tonnes.
Interactive estimator
Calculate MOT Type 1 tonnes and bags
Example: 20 m2 at 100 mm needs about 2.20 m3 or 4.40 tonnes, equivalent to 6 x 850 kg bulk bags.
Enter area, compacted depth, density, and allowance to match the project and merchant quote.
MOT Type 1 estimates for 20 m2
| Area | Compacted depth | Cubic metres | Tonnes | 850 kg bulk bags |
|---|---|---|---|---|
| 20 m2 | 75 mm | 1.65 m3 | 3.30 t | 4 |
| 20 m2 | 100 mm | 2.20 m3 | 4.40 t | 6 |
| 20 m2 | 150 mm | 3.30 m3 | 6.60 t | 8 |
| 20 m2 | 200 mm | 4.40 m3 | 8.80 t | 11 |
Assumes 10% allowance and 2.0 tonnes per cubic metre. Actual loose material and supplier bag weights vary.
How much MOT Type 1 do I need?
Calculate compacted volume from area x depth, add an allowance, then convert to tonnes using supplier density. The table uses 2.0 tonnes per cubic metre as a planning density.
For merchant orders, divide tonnes by the bag weight and round up. For loose loads, ask the supplier how they price partial tonnes.
When to use a deeper MOT Type 1 layer
Use a deeper layer for driveways, weak ground, poor drainage, or areas likely to carry heavier loads. Pedestrian patios and paths are usually less demanding than vehicle areas.
If the ground is soft or the project carries vehicles, use these numbers only for early budgeting and confirm the build-up locally.
Helpful next step
Use the calculator above for a custom MOT Type 1 order. For other granular sub-base products, use the broader UK sub-base calculator.