Quick answer

How Much MOT Type 1 Do I Need for a Patio?

Compacted sub-base under patio slabs, with 5% extra for an uneven dig.

Page last reviewed 26 October 2026 by the UkToolCalc team

A 15m² patio (5 × 3m) needs about 3.3 tonnes of MOT Type 1 at 100mm compacted: 4 × 850kg bulk bags. Each bulk bag covers about 4m² at 100mm.

Work out your own in the MOT Type 1 Sub-Base calculator

2.1 tper m³ compacted
~4m²per 850kg bag at 100mm
100mmstandard patio sub-base
75mmmax per compacted layer

MOT Type 1 by patio size

Compacted depth, 5% extra included, 850kg bulk bags.

Patio area	100mm deep	150mm deep	Membrane
10 m²	2.2 t · 3 bags	3.3 t · 4 bags	11.5 m²
15 m²	3.3 t · 4 bags	5.0 t · 6 bags	17.2 m²
20 m²	4.4 t · 6 bags	6.6 t · 8 bags	23 m²
30 m²	6.6 t · 8 bags	9.9 t · 12 bags	34.5 m²

The sum

Tonnes = area (m²) × depth (m) × 2.1 × 1.05 15m² at 100mm: 15 × 0.1 × 2.1 × 1.05 = 3.3 t

On top of the MOT goes a mortar bed for the slabs: the patio calculator does the slabs, sand and cement. The patio sub-base guide explains depths for each type of ground.

Frequently asked questions

How deep should MOT Type 1 be under a patio?

100mm compacted is standard for a garden patio on firm ground. Use 150mm on clay or soft ground, and for areas that will take heavy loads.

How much does a tonne of MOT Type 1 cover?

Compacted MOT Type 1 weighs about 2.1 tonnes per m³, so one tonne covers about 4.8m² at 100mm deep, or 3.2m² at 150mm.

Do I compact MOT in one go?

No. Lay and compact it in layers of no more than about 75mm with a plate compactor, so a 100mm sub-base is two layers.

Related calculators

MOT Type 1 Sub-Base CalculatorTonnes and bulk bags of sub-base for patios, paths and driveways.

Patio & Paving Slab CalculatorSlabs, MOT sub-base, sharp sand, cement and jointing compound.

Excavation & Muck-Away CalculatorDig volume, bulked spoil, tonnes and skips or grab lorries to remove it. Patio & Driveway Sub-Base Depth GuideHow deep to dig and how much MOT Type 1 for patios, paths, sheds and driveways.