Basic N-P-K question

Hi, i'm new to growing, im at the end of the first month of my first grow. I was wondering about something to do with N-P-K because I want to make my own organic fertilizer mix using coffee grounds, bone meal and banana peels.
I was just wondering what happens when you add two nutrients together to make a mixture.
Do their NPK readings add together?
Like, the bone meal i'm using is 4 : 12 : 0 and coffee grounds have an NPK of 2.1 : 0.3 : 0.3 so I was wondering if I had 1 part coffee ground and 1 part bone meal, would the total NPK of the mixture be
6.1 : 12.3 : 0.3?

https://www.rollitup.org/t/how-to-calculate-npk-ratio.458021/

This thread should contain the information you are requesting.

homegrownwhore said:

Like, the bone meal i'm using is 4 : 12 : 0 and coffee grounds have an NPK of 2.1 : 0.3 : 0.3 so I was wondering if I had 1 part coffee ground and 1 part bone meal, would the total NPK of the mixture be
6.1 : 12.3 : 0.3?

Click to expand...

I recently made a spreadsheet (<<link) to make it easier to play with different products to achieve an NPK ratio and PPM strength.

coffee grounds are like time release PH down

Thanks for the replies! Its been a big help