Overview
This calculator converts length, width, and thickness into concrete volume in cubic meters. It also adds a waste allowance and estimates the number of bags based on bag yield. It is useful for planning ready-mix orders or bagged concrete jobs.
Use cases
- Estimating concrete for slabs and garage floors.
- Planning footing concrete for fences and small structures.
- Calculating materials for post holes and column bases.
- Comparing bagged concrete with ready-mix orders.
How it works
- 1
Enter the length and width in meters.
- 2
Enter the thickness in centimeters.
- 3
Set the waste percentage to cover spillage and uneven surfaces.
- 4
Enter the yield of one bag in cubic meters.
- 5
Review the concrete volume, volume with waste, and bag count.
Examples
Slab estimate
Input: 4 m x 3 m x 10 cm
Output: 1.2 m3 of concrete before waste.
A simple example for a small slab or patio base.
Footing estimate
Input: 2 m x 0.5 m x 30 cm
Output: 0.3 m3 of concrete before waste.
Useful for strip footings or foundation pads.
FAQ
How do I calculate concrete volume?
Multiply length by width by thickness, then convert thickness from centimeters to meters.
Why should I add waste?
Waste covers spills, over-excavation, and small calculation errors.
Can I use this for ready-mix orders?
Yes. The volume with waste helps you estimate how much ready-mix to order.
How do I estimate bags?
Divide the volume with waste by the bag yield, then round up to the next whole bag.
Is this calculator suitable for post holes?
Yes, as long as you enter the hole dimensions as a simple rectangular equivalent or adapt the values to your project.