Concrete Volume Calculator
Work out how much concrete a slab, path or footing needs from its length, width and depth, in cubic metres, cubic yards and bags of premix.
- Free
- No sign-up to try
- Works as you type
Concrete volume
Concrete to order
1.485 m³
Bags of premix
124 bags
In cubic yards
1.94 yd³
Volume before waste
1.350 m³
- Volume = length × width × depth (depth converted from cm to m).
- Concrete to order = volume × (1 + waste allowance).
- Bags = volume in litres ÷ what one bag makes, rounded up; 1 m³ = 1.30795 cubic yards.
Free, no sign-up to try. Save it as a live calculator you can share; an estimate from the numbers you enter, not financial advice. Check the result against your own records before you rely on it.
How it works
How the Concrete Volume Calculator works
- 1
Enter your numbers
Every result updates as you type, with the formula shown under it.
- 2
Check the method
See how each number is worked out and what it assumes.
- 3
Save it as a Room
Share a live calculator: others can change the numbers and see the result update.
Worked example
What it makes
Example inputs
- Length
- 4.5 m
- Width
- 3 m
- Depth
- 10 cm
- Extra for waste and spillage
- 10 %
- Concrete one bag makes (see the bag)
- 12 L
Results
- Concrete to order
- 1.485 m³
- Bags of premix
- 124 bags
- In cubic yards
- 1.94 yd³
- Volume before waste
- 1.350 m³
How it's calculated
- Volume = length × width × depth (depth converted from cm to m).
- Concrete to order = volume × (1 + waste allowance).
- Bags = volume in litres ÷ what one bag makes, rounded up; 1 m³ = 1.30795 cubic yards.
- Assumes: The shape is a rectangle of even depth; split other shapes into rectangles and add them up.
- Assumes: What a bag makes varies by product and size: use the yield printed on yours.
An estimate from the numbers you enter, not financial advice. Check the result against your own records before you rely on it.
Who it's for
Who uses it
DIYers
Buy the right number of bags for a shed base or path.
Builders
Check a ready-mix order before you book the truck.
Landscapers
Price the concrete in a quote quickly.
Good to know
What to consider
- What one bag makes varies by product and bag size: use the yield printed on yours.
- For larger pours, ready-mix is usually more practical than bags; ask your supplier about minimum loads.
- This gives volume only; check slab depth and reinforcement for the load with a qualified builder or engineer.
Questions
About the Concrete Volume Calculator
How much extra should I order?
Ground is rarely perfectly level and some concrete is always lost, so most people add 5 to 10%. Running short in the middle of a pour is worse than having a little left over.
Can I share the calculator with my team or a client?
Yes. The Room keeps the calculator live: anyone with the link can change the numbers and see the result update, with the method and assumptions on the same page.
Make your calculator now
Free, no sign-up to try. It becomes a Room you can edit, publish and share.
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