How to use the Cement, Sand & Aggregate Calculator
- 1. Enter the volumeLength × width × depth, or the volume in m³.
- 2. Pick the mixM5 to M20 nominal ratios or your own cement : sand : aggregate.
- 3. Get materialsCement in bags and kg, sand and aggregate in m³ and cft, and water.
Method
Wet concrete shrinks when made from dry materials, so dry volume = wet volume × 1.54 (a thumb rule; 1.52 to 1.57 is also used). Split the dry volume by the mix ratio: for 1 : 1.5 : 3 the sum is 5.5, so cement = dry volume × 1/5.5.
Cement bags = cement m³ × 1440 kg/m³ / 50 kg. Water = cement kg × w/c ratio. 1 m³ = 35.31 cubic feet.
Worked example and tips
1 m³ of M20 (1 : 1.5 : 3): dry volume = 1.54 m³. Cement = 1.54 / 5.5 = 0.28 m³ × 1440 = 403 kg = 8.06 bags. Sand = 0.42 m³ (14.8 cft) and aggregate = 0.84 m³ (29.7 cft). Water at w/c 0.5 = 202 litres.
- IS 456 allows nominal mixes only up to M20. For M25 and above, use a design mix such as the IS 10262 mix design calculator.
- Add a small wastage allowance for site handling if you need one.
- Sand bulks when damp; volume batching on site should allow for it.
Frequently asked questions
How many cement bags are needed for 1 m³ of M20?
About 8 bags by the 1.54 dry volume thumb rule and 1:1.5:3 nominal mix.
Why is the dry volume factor 1.54?
Voids in dry sand and aggregate fill up when water is added, so about 54% more dry material is needed. It is an editable thumb rule.
Can I use this for M25?
Choose Custom and enter a ratio if you like, but IS 456 asks for a design mix from M25 upwards.
Is this calculator free?
Yes. You enter your name and WhatsApp number once to see your result, and all other Uncodemy tools then open without the form. Everything is calculated in your browser.