How to Calculate the Materials to Build a Patio (Complete Guide)

A patio isn't one material: it's four layers, calculated separately and bought together. This guide works through an example 4 × 3 meter (13 × 10 ft) patio from start to finish — gravel base, concrete slab, tile finish, and perimeter garden — so you can repeat the process with your own measurements.

The example project

A 4 × 3 m (12 m² / ~130 sq ft) patio on natural ground, with an exterior tile finish and a 50 cm (20 in) garden strip around it. The layers, bottom to top: compacted gravel base (10 cm), concrete slab (10 cm), exterior tile bonded to the slab, and the perimeter with soil and mulch. Each step uses one of the site's calculators; here we show the full arithmetic.

Step 1 — Compacted gravel base

The base drains water and stabilizes the slab. Volume: 4 × 3 × 0.10 = 1.2 m³. Gravel loses 10–15% of its volume when compacted, so order 15% extra: 1.2 × 1.15 ≈ 1.4 m³ of 3/4" gravel (about 2.2 tons at a typical 1,600 kg/m³ density). Tip: lay geotextile fabric under the gravel so it doesn't sink into the soil over the years. → Gravel calculator

Step 2 — Concrete slab

Volume: 4 × 3 × 0.10 = 1.2 m³; with 10% waste, 1.32 m³. In 50 kg premixed bags (0.0225 m³ yield): 1.32 ÷ 0.0225 = 58.7 → 59 bags. From ~2 m³ up it's worth quoting ready-mix by truck as well: at 12 m² we're right at the border, and a continuous truck pour usually gives a better finish on large slabs. Don't forget welded wire mesh (12 m² + overlaps ≈ 14 m²) and curing: wet the surface 2–3 times a day for 7 days. → Concrete calculator

Step 3 — Exterior tile finish

Area: 12 m². With a straight lay and 10% waste: 13.2 m² to buy. With 33 × 33 cm tiles (9 per m²) that's ~119 pieces; in 1.2 m² boxes, 11 boxes. Buy all boxes from the same batch (tone varies between batches) and choose a slip-resistant tile for outdoors. Adhesive: bags state coverage per m² by trowel size — for 12 m² with a 6 mm trowel, figure 4–5 bags of 20 kg. → Tile calculator

Step 4 — The perimeter garden

The 50 cm strip around the patio adds (5 × 4) − (4 × 3) = 8 m². For planting beds: 15 cm of improved soil = 8 × 0.15 = 1.2 m³; with 15% for settling, ~1.4 m³. On top, 5 cm of mulch = 0.4 m³ = 400 liters → in 50 L bags, 9 bags (with margin). → Soil calculator and mulch calculator

Final shopping list

3/4" gravel	1.4 m³ (~2.2 t) + 14 m² geotextile fabric
Bagged concrete (50 kg)	59 bags + 14 m² welded wire mesh
Exterior tile 33×33	11 boxes (13.2 m²) + 4–5 bags of adhesive + grout
Improved soil	1.4 m³
Mulch	9 × 50 L bags

Work order and timing

The right sequence avoids redoing work: excavate and level → geotextile and compacted gravel → formwork and mesh → pour the slab → 7 days of curing (tile shouldn't be bonded before the slab finishes its initial shrinkage; ideally 14–28 days) → tile and grout → soil and mulch last, so the construction doesn't trample them. A patio like this is perfectly doable on weekends: one for the base, one for the pour, and the finish once the concrete is ready.