Concrete · 6 min read

How Much Concrete Do You Need for a 5×5 Slab?

Step-by-step volume math for a 5×5 slab, thickness tips, waste allowance, and when to use our interactive concrete calculator.

Use with our Concrete Calculator.

Pouring a small slab starts with one question: how many cubic meters (or cubic feet) of concrete do you actually need? For a 5×5 footprint, the answer depends almost entirely on thickness — not just length and width.

Quick answer for a 5×5 slab

Volume

Volume = length × width × thickness

Use the same units throughout (meters recommended).

5 m × 5 m at 100 mm (0.1 m) thick

5 × 5 × 0.1 = 2.5 m³ of concrete. Add 5–10% waste → order about 2.6–2.8 m³.

5 ft × 5 ft at 4 in (0.33 ft) thick

5 × 5 × 0.33 ≈ 8.3 cu ft. In cubic yards that's roughly 0.31 yd³ — often less than one short load.

Estimation workflow

  1. 1

    Measure dimensions

    Length, width, and thickness in consistent units (meters or feet).

  2. 2

    Calculate volume

    Multiply all three dimensions to get cubic volume.

  3. 3

    Add waste factor

    Include 5–10% extra for spillage, uneven subgrade, and variation.

  4. 4

    Order materials

    Check local minimums, delivery constraints, and bag vs. ready-mix options.

Pre-pour checklist

  • ✓Confirm soil compaction and drainage slope
  • ✓Check local codes for required thickness
  • ✓Verify delivery access for concrete truck
  • ✓Gather tools: forms, level, release agent, screed

Material options comparison

MaterialCoverageBest forNotes
Ready-mix concreteAny volumeMost slabsMinimum delivery ~1–2 yd³
Concrete bagsSmall jobs< 0.5 m³Mix as-needed, labor intensive
Concrete trucksLarge poursDriveways, foundationsOrder 1–2 days ahead

Choosing slab thickness

  • Garden stepping paths: 75–100 mm (3–4 in)
  • Patios and light use: 100–125 mm (4–5 in)
  • Driveways: 100–150 mm (4–6 in) depending on load
  • Structural work: follow engineering specs and local code

Common estimation errors

  • Entering 100 mm as '100' in a meters field (100 m slab!)
  • Forgetting the gravel base — it's not part of concrete volume but affects prep height
  • Skipping waste — a partial pour is expensive to fix

Open interactive concrete calculator

Adjust 5×5 (or any size), thickness, and see volume + visual slab instantly.

Open calculator →

Related guides

View all planning guides →