DME Adjustment Math

Hi folks, I am sure this is answered somewhere and I have been searching to no avail...

I am prepping for my first AG this week, and getting all my ducks in a row. I have some DME on hand in case I miss my OG. I just wanted to make sure my DME Math was right...

I had read that 1lb DME / 1 gallon = 43 gravity points. Is the conversion linear?

For example:
1lb DME added to 4 gallons would increase the Gravity approx. 11 Gravity points?
-OR-
.5lb DME to 1 gallon would increase the Gravity approx. 21 Gravity points?


etc., etc...

Thanks!

Yeah, you are right on.

Sweet, thanks