Grade of concrete (concrete mix design)

Grade of concrete (concrete mix design)  is the design-mix of concrete according to its compressive strength.

The concrete grades are denoted by M5, M7.5, M10, M15, M20, M25 etc according to their compressive strength.

The “M” denotes Mix design of concrete followed by the compressive strength number in N/mm2 (MPa)[mega pascal]

If we consider a mix of M20, than we can define it as

The grade of concrete concrete can be further classified as Normal grade of concrete, Standard grade of concrete and High strength grade concrete based on the compressive strength and the area where the concrete is going to be used.

Concrete above M-25 grades are been designed based on the compressive strength required and the characteristics required for concrete performance such as workability, heat of hydration etc. These designed concrete is known as Design-Mix concrete.

As per IS 456:2000 the  chart shows the different grades of concrete with its compressive strength in Mpa and PSI.

Concrete Grade	Mix Ratio	Compressive Strength
		MPa (N/mm2)	PSI
Normal Grade Of concrete
M5	1:5:10	5 MPa	725 psi
M7.5	1:4:8	7.5 Mpa	1087 psi
M10	1:3:6	10 MPa	1450 psi
M15	1:2:4	15 MPa	2175 psi
M20	1:1.5:3	20 MPa	2900 psi
Standard Grade Of Concrete
M25	Design Mix	25 MPa	3625 psi
M30	Design Mix	30 MPa	4350 psi
M35	Design Mix	35 MPa	5075 psi
M40	Design Mix	40 MPa	5800 psi
M45	Design Mix	45 MPa	6525 psi
High Strength Concrete Grade
M50	Design Mix	50 MPa	7250 psi
M55	Design Mix	55 MPa	7975 psi
M60	Design Mix	60 MPa	8700 psi
M65	Design Mix	65 MPa	9425 psi
M70	Design Mix	70 MPa	10150 psi