Concrete Calculator
Calculate concrete volume in cubic yards, feet and metres for slabs and columns. Get cement bags, weight and ready-mix vs bag cost with waste allowance.
Number of identical elements.
5–10% covers spillage and uneven ground.
Concrete volume
2.25 m³
2.94 yd³ · 79.5 ft³
Weight
5,400 kg
5.4 tonnes
50 kg bags
114
Includes 5% waste · 114 × 50 kg
Material cost
₹39,900 (bags)
₹14,175 ready-mix — pick the cheaper route
Assumes 2,400 kg/m³ density and 5% waste. Volume and bag count include the waste allowance.
How it works
Volume = L × W × D. Weight = volume × 2,400 kg/m³. Bags = weight ÷ bag size.
Example: 5 × 3 × 0.15 m = 2.25 m³ ≈ 5,400 kg ≈ 108 bags of 50 kg.
Last updated: August 2026
How this calculator is verified
Checked by Rahim Virani on
- Volume computed for slab, footing and column shapes separately
- Mix ratio (1:2:4 etc.) converted to dry volume using the standard 1.54 bulking factor
- Bag count rounded up so the order covers the pour rather than falls short
The full verification method is on our how we verify page. Found an error? Tell us and we will re-check it.
When to Use This Calculator
The concrete calculator is what you open before ordering ready-mix or cement bags for any slab work in India — a house plinth, a boundary-wall footing, a veranda floor or a toilet platform in a village home. Contractors quote per cubic metre of concrete and per bag of cement, so converting the site measurements into both units keeps a verbal quotation honest. The bag count depends on the mix ratio, which is why the page explains how the figure changes with a 1:2:4 mix versus a richer 1:1.5:3 mix. Buyers also use the weight figure when arranging delivery, since ready-mix is billed per cubic metre and small loads attract extra charges. Run the same slab at two depths to see how a 5 cm measurement error changes the volume before the material is ordered.
How to Use This Calculator
- Step 1: Measure the slab in metres — length, width and depth — using a tape and a consistent unit.
- Step 2: Enter the three measurements in the length, width and depth fields.
- Step 3: Read the volume in cubic metres and cubic feet, and the total weight.
- Step 4: Note the bag count shown for 50 kg and 40 kg cement bags, then confirm the actual mix ratio with your supplier before ordering.
Worked Example
You are casting a small plinth slab 4 metres long, 3 metres wide and 15 centimetres deep. Convert the depth to 0.15 metres and enter 4, 3 and 0.15. The tool computes 1.8 cubic metres of concrete, about 4,320 kilograms of wet mix using the standard 2400 kg per cubic metre density, and 87 bags of the 50 kg size. The bag figure assumes a specific mix, so treat it as a planning number. A depth error of 5 centimetres changes the volume by about a third, so measure twice.
Tips and Common Mistakes
- •Tip 1: Convert every measurement to metres before entering — 15 cm must be typed as 0.15 m, or the volume comes out 100 times too large.
- •Tip 2: Order roughly 5 to 10 percent extra for spillage and uneven ground, especially on small sites where losses matter more.
- •Tip 3: Check whether your supplier prices ready-mix by the cubic metre and bags by the piece, since the two quotes are easy to compare once volumes match.
- ✗Mistake 1: Mixing units — entering the length in feet and the depth in metres gives a volume with no real meaning.
- ✗Mistake 2: Using the bag count without checking the mix ratio; a 1:2:4 mix needs different cement per cubic metre than a richer 1:1.5:3 mix.
Frequently Asked Questions
How much concrete do I need for a slab?
Multiply length × width × thickness. A 5 m × 3 m × 0.15 m slab is 2.25 m³, weighing about 5.4 tonnes — roughly 108 bags of 50 kg cement mix.
How many cement bags are in 1 cubic metre?
Assuming 2,400 kg per m³ of mixed concrete and 50 kg bags, one cubic metre needs about 48 bags of dry mix.
How much extra concrete should I order?
Add 5–10% for spillage, uneven subgrade and formwork inaccuracies. For a 2.25 m³ slab, order about 2.4 m³.
How thick should a concrete slab be?
Garden paths around 10 cm, patios and sheds 10–15 cm, and driveways 15–20 cm with reinforcement. Thinner slabs crack under vehicle loads.
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