Construction estimator
Cement-Sand-Aggregate Calculator
Already know the volume of concrete and the mix ratio? Enter them to see the cement bags, sand and aggregate to buy. Your entered values stay out of analytics.
Formula and assumptions
Order volume = entered volume × (1 + wastage). Dry volume = order volume × 1.54. Each material = dry volume × its part ÷ (cement + sand + aggregate parts). Cement bags = cement volume × 1,440 kg/m³ ÷ 50 kg, rounded up to buy.
- You enter a volume of finished (wet) concrete and a mix ratio by volume (cement : sand : coarse aggregate).
- Dry volume is 1.54 times the wet volume, the usual factor for shrinkage and voids.
- Bulk densities: cement 1,440 kg/m³, sand 1,600 kg/m³, coarse aggregate 1,500 kg/m³. Cement is bought in 50 kg bags.
- Wastage is added to the wet volume before the dry volume is worked out.
- An estimate for buying materials. It does not cover steel, shuttering, water, admixtures, sand bulking or structural design.
- A custom ratio is a site convenience, not an IS 456 mix.
- Volumes and masses are shown to 2 decimal places. Cement bags to buy are rounded up to a whole bag; sand and aggregate are not rounded to loads.
Formula version 1.0, last reviewed Reviewed by an external trade reviewer, 6 October 2026; released by the owner.
Frequently asked questions
How is this different from the Concrete Calculator?
The Concrete Calculator starts from the length, width and thickness of the member. This one starts from a volume you already have and lets you use your own mix ratio. For the same volume and ratio they give the same materials.
What does the ratio mean?
Parts by volume of cement, sand and coarse aggregate. 1 : 2 : 4 is one part cement, two parts sand and four parts aggregate.
Is a custom ratio an approved mix?
A custom ratio is a quantity-estimation input. It does not establish a concrete strength grade or constitute a structural concrete mix design. The presets offered are M5 to M20. M25 and above need a specified or design mix. A ratio that is richer than 1 : 1 : 2 or leaner than 1 : 5 : 10 is flagged as unusual, and you should confirm the project mix specification before ordering.
What does this not include?
Reinforcement steel, shuttering, water, admixtures, sand bulking from moisture, mortar and plaster mixes, and any structural design. It is an estimate for buying materials.