How Many Paving Slabs for a 5m x 4m Patio?

A 5 × 4 m patio (20 m²) needs 60 paving slabs of 600 × 600 mm, including 10% for cuts, plus about 4.6 tonnes of MOT Type 1 sub-base and 1.01 tonnes of sharp sand for the bed. Pick a different slab size in the calculator below.

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Paving slabs to buy

60 slabs

2.69 slabs per m², with your cutting allowance

Area: 20.0 m²

Sub-base

MOT Type 1 sub-base2.10 m³ compacted, with 5% extra: 4.62 tonnes

Bedding sand

Sharp sand: 1.01 tonnes

Assumptions used: 10% waste added; 10 mm joints; MOT Type 1 at 2.2 tonnes/m³ compacted; 5% extra on the sub-base and bed; a 30 mm sharp sand bed with sand at 1.6 tonnes/m³.
MOT Type 1 weighs about 2.2 tonnes per m³ once compacted, so 100 mm needs about 0.22 tonnes per m². Quantities include 5% extra for the sub-base and the bed. The mortar figures are approximate: allow for the dry materials being about 1.3 times the wet volume of the mortar.

Before you buy: round up to whole packs, check the size printed on the label, and add a little spare. Your supplier has the final say.

Slabs, sub-base and sand for a 5 × 4 m patio

These figures are for the whole 20 m² patio with 10 mm joints and 10% for cuts. The sub-base is 100 mm of MOT Type 1 and the bed is 30 mm of sharp sand. Bigger slabs mean fewer to lay but more weight each.

Slab size	Slabs to buy	MOT Type 1 (tonnes)	Sharp sand (tonnes)
600 × 600 mm	60	4.6	1.01
450 × 450 mm	104	4.6	1.01
300 × 300 mm	229	4.6	1.01
600 × 300 mm	117	4.6	1.01
900 × 600 mm	40	4.6	1.01

What a 5 × 4 m patio is used for

This size suits a family patio with a dining set and a lounge corner. Allow a fall of about 1 in 80 away from the house so rain runs off, and keep the finished level at least 150 mm below the damp-proof course.

Sand bed or mortar?

A sand bed is the usual DIY choice. A full mortar bed (6:1 sand to cement) is stronger for a drive or heavy use: it needs about 1.50 tonnes of the sand and cement mix for this patio, instead of 1.01 tonnes of sharp sand. A sub-base of 150 mm (6.9 tonnes) is better where cars will drive on it. Check the planning rules for paving a front garden: more than 5 m² of impermeable surface needs permeable materials or drainage.

See the full patio materials calculator for the edging, mortar and tools as well.

Want to change anything else? The calculator above is the full Paving Slab Calculator (UK): edit any number and the results update instantly.

Tools & materials for this project

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Paving slabs (600 × 600 mm)Rubber mallet Paving jointing compound Angle grinder with diamond blade Spirit level (1.8 m)

Frequently asked questions

How many paving slabs do I need for a 5m x 4m patio?

A 5 × 4 m patio is 20 m². With 600 × 600 mm slabs, 10 mm joints and 10% for cuts you need 60 slabs. With 450 × 450 mm slabs it is 104, and with 900 × 600 mm slabs it is 40.

How much sub-base and sand for a 5m x 4m patio?

A 100 mm sub-base of MOT Type 1 is about 4.6 tonnes (6.9 tonnes at 150 mm for a drive), and a 30 mm sharp sand bed is about 1.01 tonnes. Buy bulk bags or a loose delivery rather than bags if you can.

How many 600x600 slabs in a 5m x 4m patio?

60 slabs of 600 × 600 mm, which includes 10% for cuts and breakages. Without any waste allowance the count is 54.

Related sizes and guides

Related sizes

Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.

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