Concrete Calculator
To calculate concrete volume, multiply length × width × depth. For most projects, add an extra 5–10% to account for waste, uneven ground, and spillage. Enter your dimensions below—the tool converts everything to meters internally, then shows volume (m³, ft³, yd³) and weight (t, kg, lbs) using 2400 kg/m³ unless you override density.
For thin slabs, see the concrete slab calculator. For strip footings, use the concrete footing calculator.
Rectangular concrete pour
Calculation is based on average density of 2400 kg/m³.
Calculation Results
Concrete volume
0.00 m³
Concrete weight
0.00 t
How much concrete do you actually need?
Concrete is one of those materials where small miscalculations turn into real money fast. If you are short, the pour stalls while you wait on another truck. If you overorder, you pay for material you cannot use. This calculator turns your dimensions into net volume and estimated weight so you can line up orders with less guesswork—then you still add that 5–10% safety margin on top.
How this concrete calculator works
The calculation is straightforward:
- Volume = length × width × depth
- Weight = volume × concrete density
We use a standard density of 2400 kg per cubic meter, which is typical for normal structural concrete. Everything you enter is converted to a consistent unit internally, so you can mix feet, meters, inches, or yards without hand-converting each step.
When you should use this calculator
This tool fits simple, box-shaped pours such as:
- Concrete slabs for patios or garages
- Driveways and walkways
- Footings and foundation bases
- Shed and outbuilding pads
If your project is a rectangular or square pour, you get a clear volume and weight check in one pass.
Real-world example
Say you are pouring a small patio:
- Length: 10 ft
- Width: 10 ft
- Depth: 4 in
That works out to roughly 0.94 m³ of concrete and about 2.3 metric tons at 2400 kg/m³. Add 5–10% on top of that for waste and variation, then round to your supplier’s minimum load or truck size—not to the bare net number.
Common mistakes to avoid
- Forgetting depth conversion. Depth is often measured in inches while length and width are in feet. This calculator keeps each dimension with its own unit so the depth is converted correctly.
- Ignoring uneven ground. A low spot in the subgrade eats more concrete than a flat sketch assumes. Grade and compact before you trust the number.
- Not adding extra material. Mixing, hauling, and pouring always involve some loss. Do not order the exact net volume from the formula alone.
- Assuming all concrete is the same. Lightweight or specialty mixes can differ in density. For unusual mixes, switch on manual density and enter the value from your supplier.
Practical tips before you pour
- Compact the base properly before you place concrete.
- Use formwork that will hold shape under the pressure of wet concrete.
- Plan timing so you do not trap cold joints you did not intend.
- On large slabs, ready-mix and a pump often beat hand-mixing for consistency and speed.
Frequently asked questions
How thick should a concrete slab be?
For most residential uses, 4 inches is a common thickness. Driveways or load-bearing slabs may require 5–6 inches or more, depending on loads and local code.
Should I order concrete in cubic meters or tons?
Suppliers usually sell by cubic meter or cubic yard. This calculator shows both volume and mass so you can match quotes and truck limits.
Do I really need extra material?
Yes. Include at least 5% extra on small jobs—often 10% on irregular sites—to avoid running short mid-pour.
What if my area is not perfectly rectangular?
Split the area into smaller rectangles, calculate each separately, and sum the volumes. Irregular shapes may need a more detailed takeoff.