What strength of 1:3 cement mortar is equivalent to M?

The strengths are as follows:

The standard strength of 1:3 cement mortar is generally equivalent to about M15. But note that 1:3 is not a mass ratio, but a volume ratio of raw materials. Usually said 1:3 cement mortar is with 1 weight cement and 3 weight sand with, in fact, ignored the water component, generally in the proportion of about 0.6, that should become 1:3:0.6, the density of cement mortar is 2000Kg/m3.

Introduction:

Cement mortar is made of cement, fine aggregates and water, i.e. cement + sand + water, according to the need to formulate the mortar, and cement mixed mortar is formulated from cement, fine aggregate, lime and water.

The two are different concepts, called differently and used for different purposes. Cement mortar and ready-mixed masonry mortar strength grade can be divided into M5, M7.5, M10, M15, M20, M25, M30.