What a Concrete Slab Costs: Step-by-Step Budgeting Method

Material prices change by region and season, so any "slab price" published online expires within weeks. What doesn't expire is the method: the 5 line items that make up the cost and the exact quantities of each. This guide works them out for an example 3 × 2 m × 10 cm slab (about 10 × 6.5 ft × 4 in) — multiply each quantity by your local price and you'll have a serious budget in 15 minutes.

The 5 line items of any slab

1. Concrete	Premixed bags or ready-mix truck
2. Reinforcing steel	Welded wire mesh (or rebar, in structural slabs)
3. Formwork	Wood or metal to contain the pour at the edges
4. Base and preparation	Gravel or compacted material under the slab; leveling
5. Labor	Pouring, screeding, finishing, and curing

Item 1 — The concrete (the biggest one)

Volume: 3 × 2 × 0.10 = 0.6 m³; with 10% waste, 0.66 m³. In 50 kg bags (0.0225 m³ per bag): 30 bags — exactly the default example in our concrete calculator. Add water: each bag takes 4–5 liters, about 150 L total. If ready-mix by truck is sold by the m³ or yd³ in your area, quote both options: for small volumes like this, bags almost always win because trucks charge minimum volume plus delivery.

Item 2 — Welded wire mesh

For patios and non-structural slabs, 6-6/10-10 mesh is the reference. Area: 6 m² + 15% overlaps = 7 m². Sold by roll or sheet — convert to your supplier's units. Place it at mid-depth (use spacers or "chairs"), not lying at the bottom: mesh at the bottom of a slab does no work.

Item 3 — Formwork

Perimeter: 2 × (3 + 2) = 10 linear meters (33 ft) of boards at least 10 cm tall, plus stakes every ~80 cm (13 stakes). Formwork lumber is reusable: if you'll pour again, remove it carefully.

Item 4 — Compacted base

On firm natural ground, compacting and leveling is enough; on fill or expansive clay, add 5–10 cm of compacted gravel: 6 m² × 0.08 m × 1.15 ≈ 0.55 m³. The base is the difference between a slab that lasts decades and one that cracks in its first year. → Gravel calculator

Item 5 — Labor (and how to get quotes)

Labor is quoted per m² (or per sq ft) in most regions. To compare quotes fairly, ask them all to include the same scope: base preparation, formwork, pour, finish (troweled or broomed), and curing. A "cheap" quote that excludes finishing and curing isn't cheap. Structural reference: labor usually represents between a third and half of the total cost of a small slab.

The budget template

30 × 50 kg concrete bags	30 × local price per bag
6-6/10-10 mesh (7 m²)	per local presentation
Formwork: 10 linear m + 13 stakes	local lumber (reusable)
Base gravel (0.55 m³, if applicable)	0.55 × price per m³
Labor, 6 m²	6 × local price per m² (all-inclusive)

Two final tips: add 5–10% contingency to the total, and distrust any budget that doesn't start from quantities — if nobody counted the bags, nobody knows what it will cost. The quantities above take 2 minutes with the calculator; the judgment comes from this guide.