Concrete Calculator
Calculate how much concrete you need for a slab, path, or foundation. Volume and bag estimates.
Dimensions
Your Results
~60 x 25kg or ~40 x 40kg bags per m³. Buy 10% extra.
What is a Concrete Calculator?
A concrete calculator helps you estimate the volume of concrete needed for a project—whether a patio slab, driveway, path, or foundation. It converts dimensions into cubic metres (or cubic yards) and estimates the number of bags required.
The Formula
Volume = Length × Width × Depth
- Metric: Length (m) × Width (m) × Depth (cm ÷ 100) = m³
- Imperial: (Length × Width × Depth in inches) ÷ 46656 = yd³ (or ÷ 27 for depth in feet)
Bag Estimates
- 25 kg bags: Approximately 60 bags per cubic metre
- 40 kg bags: Approximately 40 bags per cubic metre
These are estimates; check the coverage on your specific product.
Example
- Slab: 5m × 3m × 10cm
- Volume: 5 × 3 × 0.10 = 1.5 m³
- Bags (25kg): ~90 bags
- Bags (40kg): ~60 bags
How Our Calculator Works
- Enter dimensions: Length, width, depth
- Choose units: Metric (m, cm) or Imperial (ft, in)
- Get results: Volume and bag estimates
Frequently Asked Questions
How much concrete do I need for a 10x10 slab?
For 4 inches thick: (10 × 10 × 0.33) ÷ 27 ≈ 1.2 cubic yards. For 10cm: 10m × 10m × 0.10m = 10 m³.
Should I buy extra?
Yes. Buy 5-10% extra for wastage, uneven ground, and spillage.
What depth for a driveway?
Typically 4-6 inches (10-15 cm) for cars. Heavier vehicles need more.
Related Tools
Gravel Calculator
Calculate how much gravel you need for a driveway, path, or landscaping. Volume and weight estimates.
Paint Coverage Calculator
Calculate how much paint you need for a room or wall area. Enter room dimensions or total area, number of coats, and coverage rate.
Unit Converter
Convert between different units of measurement including length, weight, and temperature.