Build a Patio Estimator

Work out the slabs or pavers, sub-base, sand and cement needed to lay a patio of any size.

Part of:Project Estimators hub
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How to Use This Calculator

How to Use

  1. Choose metric or imperial units.
  2. Enter the overall patio length and width.
  3. Pick your slab size and set the sub-base depth (100 mm is typical for a patio).
  4. Add a waste allowance for cuts and breakages.

What this estimates

You get the number of paving slabs, the MOT Type 1 sub-base in tonnes, the sharp sand for a bedding layer, and the cement for a bedding mortar. For a full mortar bed, sand and cement are mixed roughly 5:1.

Common Questions

How deep should a patio sub-base be?

For a domestic patio, 100 mm of compacted MOT Type 1 over firm ground is usually enough. For a patio that takes vehicle loads, increase it to 150 mm.

Should I lay slabs on a full mortar bed or dabs?

A full mortar bed is strongly recommended for patios — it supports the whole slab and prevents rocking and cracking. Spot or dab bedding is not suitable for areas that take foot traffic.

How much waste should I allow for cuts?

Allow about 10% for a rectangular patio, or up to 15% if there are curves, angles or lots of cuts around features.

What goes under a patio?

Typically a compacted MOT Type 1 sub-base, a mortar or sand-and-cement bedding layer, then your slabs. The estimator lists quantities for each.

How much fall should a patio have for drainage?

Aim for a slope of about 1:80 (roughly 12 mm per metre) away from the house so rainwater drains off rather than pooling.

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