What's the correct mixture for concrete?

[ruby2020]

I want to lay concrete on the stair steps in my backyard. I have the sand and blue metal and bags of cement. I want to know how much sand and blue metal I should mix with one 20kg bag of cement.

[MitchellMc]

Welcome to the Bunnings Workshop community @ruby2020. It's brilliant to have you join us, and many thanks for your question about mixing concrete.

Just so you are aware, it would likely be easiest to use pre-mixed concrete rather than mixing your own. However, if you'd like to mix your own, typically, you'd use three parts blue metal, two parts sand and one part cement. This is called a 3:2:1 mix and is suitable for most concreting applications. So, you'd be using 60kg of blue metal, 40kg of sand and 20kg of cement. 

Please let me know if you have any questions.

Mitchell