How do I calculate the water-cement ratio for concrete?

The ratio between the weight of water to the weight of cement in the concrete mix is called Water Cement (W/C) ratio.

Normally, the water cement ratio being between 0.4 to 0.6 as per IS standard.

We take 0.42 as a ratio of W/C.

Quantity of water = 0.42 x 50 = 21 Liters (1 bag cement = 50 Kg)

So the required quantity of water is 21 Liters per cement bag.

Thumb Rule?

M15 Ratio 1:2:4

cement = 317 Kg (unit weight = 1440 kg/cum)

Sand = 638 Kg (unit weight = 1450 Kg/cum)

Blue Metal = 1478 Kg (unit weight = 1680 Kg/Cum)

Total = 316.8+638+1478 = 2433 Kg

unit weight of Water = 1000 Kg

Water ratio = 1000/2433 = 0.41

By this method you can calculate the water-cement ratio for concrete.