There’re many types of concrete and grades of concrete (e.g. Ready mix, Precast, Reinforced conc). In Calculation of concrete, first of all Multiply **Length** and **Width** & **Hight** to get **Volume**. It is same as Plaster/mortar calculation.

Let suppose a slab of single story house which has **50 fee**t length and **25 feet** width.

**Length= 50 ft**

**Width= 25 ft**

**Area of slab = L×W**

Area of slab = 50’×25′ = **1250 **sft or **138.9 sqyd**

**Thickness of slab = 6 inch** = 0.5 ft (That commonly used)

**Wet Volume of Concrete** = Area × Thickness of slab

**Wet Volume=1250×(6/12) = 625 Cft**

- 6 divided by 12 to convert inch into foot

**Dry Volume of concrete** = 625×1.54= **962.5 **Cft or **27.25** cu.m (35.31cft = 1 cu.m)

“It is compulsory to multiply with 1.54, to convert wet volume of concrete into dry volume (because addition & evaporation of water cause shrinkage in concrete mix, which ultimately decrease in volume).”

Dry volume means you need **962.5** Cft concrete for **25’x50′ **slab.

**How to calculate Yards of concrete?**

**Calculate volume in Feet****Multiply with 1.54 (to convert into dry volume)****Divide by 27 to convert into Cubic Yards.**

**Now we will use dry volume in concrete calculation to get Quantity of Cement, Sand & Aggregate** **for 1:2:4 concrete mix calculation**.

**Ratio of concrete mix (Grade M15) = 1:2:4**

**Sum of ratio = 7**

## Cement quantity in Concrete:

**Quantity of****Cement = (1÷7)×962.5 = 137.5**Cft**Cement = (1÷7)×27.25 = 3.9**Cum

Density of cement = 1440kg/m^{3} or 40.77kg/cft

- Multiply cft with 40.77 & cum with 1440 to get quantity of cement in KGs.

**Cft>>> 137.5×40.77= 5606 Kg**

**Cum>>> 3.9×1440= 5606 kg**

How to calculate cement bags in concrete? To find cement Bags divide by 50 (50 kg in one bag of cement).

**5606/50 = 112 bags of cement**

**Or** directly calculate cement bags from Volume:

**Volume of cement bag= 0.034cum or 1.226cft**

**Cft>>> 137.5÷1.226 = 112 Bags**

Read also Plaster/mortar calculation.

## Calculation of sand in Concrete:

**Quantity of****Sand = (2÷7)×962.5 = 275**Cft**Sand = (2÷7)×27.25 = 7.78**Cu.m

**Density of sand is 1600kg/m ^{3} OR 45.30 kg/cft**

Read also Brick calculation.

## Calculate aggregate quantity in Concrete:

**Quantity of****Aggregate = (4÷7)×962.5 = 550**Cft**Aggregate = (4÷7)×27.25 = 15.57**Cu.m

## Calculation of *Water Cement Ratio* in concrete:

- Water cement ratio means quantity of water against cement (in kgs).
- W-C Ratio = 50% × Quantity of cement (kg)
- Water= 5606×0.50 =
**2803 liters**.

50% of water quantity is commonly used in ordinary concrete mix , but it can be b/w 22% to 50%.