Add the requested inputs
Use the labelled fields in the workspace above. If example values are provided, try them first or replace them with your own.
Home & lifestyle · Free online tool
Concrete calculator
Estimate concrete volume and bags for a slab, path or pad from length, width and depth.
3 guest runs per rolling 24 hours10 with a free accountPrivate inputsMobile-friendly
Concrete calculator workspace
Runs locally in your browser
Bag coverage varies by mix and depth; confirm the coverage printed on the product.
Result
Volume—
Bags needed—
Estimated cost—
Ordering note
Use it with confidence
How to use the concrete calculator.
Calculate and review
Use the main action when needed. Volume = length × width × depth. Bags = volume ÷ declared volume per bag, rounded up to whole bags.
Try a worked example
A 2 m × 1 m slab at 10 cm deep is about 0.2 m³, or 20 bags at a 0.01 m³-per-bag coverage.
Check the assumptions
Mix coverage varies by product, water ratio and site conditions; add a small contingency and check the bag before ordering.
A clearer answer
How many bags of concrete do I need?
Enter slab length, width, depth and the volume per bag. The calculator returns volume, whole bags and optional material cost.
See the useful decision, not only one number.
It keeps bag coverage visible and lets you compare products by their declared cubic metres per bag instead of guessing from a brand name.
Worked example: 2 m × 1 m × 10 cm
Volume is 0.2 m³; at 0.01 m³ per bag that is 20 whole bags.
Method: Volume = length × width × depth. Bags = volume ÷ declared volume per bag, rounded up.
Common mistakes to avoid.
- Using the wrong bag coverage from the product label
- Forgetting compaction, spillage and uneven ground
- Rounding down instead of up
- Buying the full quantity before confirming the mix and depth
Use the result with the right assumptions.
Mix coverage varies by product, water ratio and site conditions. Add a small contingency and check the bag label before ordering.
Helpful answers
Concrete calculator FAQs.
Is the concrete calculator free?
Yes. Guests receive 3 runs per rolling 24 hours, verified free accounts receive 10, and Premium subscribers receive unlimited normal use.
Does UtilHub upload or save my inputs?
No. This tool runs in your browser and UtilHub does not receive or store the values you enter. Your browser or device may still retain normal local history or form data.
How does this concrete calculator work?
Volume = length × width × depth. Bags = volume ÷ declared volume per bag, rounded up to whole bags.
What should I check before using the result?
Mix coverage varies by product, water ratio and site conditions; add a small contingency and check the bag before ordering.
What does volume per bag mean?
A bag's coverage is usually printed on the product and depends on the mix and water ratio. The default 0.01 m³ is an editable starting point for common 20–25 kg general-purpose bags.
Does the calculator include waste?
No. It returns the theoretical volume and whole bags. Add a small contingency manually because spillage, compaction and site conditions change the practical quantity.