Concrete Calculator (Cement, Sand, Aggregate)
Volume and material quantity for slabs, beams, columns and footings in M10 to M25 nominal mix.
Assumptions and material rates (optional)
1 bag cement = 50 kg = 0.0347 m³ (density 1440 kg/m³). 1 m³ = 35.3147 cft.
| Material | Quantity | In cft / other | Cost |
|---|
Free tool by EngineeringNepal.com.np · Results are for guidance; check critical figures with a qualified engineer.
How the concrete quantity is worked out
Site engineers in Nepal still use nominal mixes such as 1:2:4 and 1:1.5:3 for small buildings, and the materials are ordered in bags of cement and cft of sand and gitti. This calculator follows the usual dry volume method taught in estimating and costing:
- Wet volume = length × width × thickness × number of members (or π/4 × D² × H for round columns), plus wastage.
- Dry volume = wet volume × 1.54. The extra 54% covers voids between particles and bulking of sand.
- Each material = dry volume × its share of the ratio. For M20 (1:1.5:3) the total is 5.5 parts, so cement is 1/5.5 of the dry volume.
- Cement bags = cement volume × 1440 kg/m³ ÷ 50 kg.
Example: 1 m³ of M20 concrete
Dry volume = 1.54 m³. Cement = 1.54 × 1/5.5 = 0.28 m³ = 403 kg = about 8.1 bags. Sand = 0.42 m³ (14.8 cft). Aggregate = 0.84 m³ (29.7 cft).
| Grade | Nominal mix | Cement bags per m³ | Common use |
|---|---|---|---|
| M10 | 1:3:6 | 4.4 | PCC below footings, levelling course |
| M15 | 1:2:4 | 6.3 | Floor base, lintel in small works |
| M20 | 1:1.5:3 | 8.1 | RCC slabs, beams, columns in houses |
| M25 | 1:1:2 | 11.1 | Heavier RCC work (design mix is preferred) |
Frequently asked questions
How many bags of cement are needed for a 1000 sq ft slab?
A 5 inch (0.127 m) thick slab of 1000 sq ft is about 11.8 m³. In M20 that needs roughly 95 to 100 bags of cement including a little wastage. Enter your exact size above to check.
Should I use nominal mix or design mix?
For M25 and above, and for any structure designed to NBC and IS 456, a design mix tested in a lab is the better choice. Nominal mix figures are fine for estimates and small residential work.
For reinforcement, use the steel weight calculator.
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