# Determine honey density and needed volume for target starting gravity

Suppose I have honey of unknown specific gravity. I want to mix a mead must with a target specific gravity g_t and volume V_t. How do I determine how much honey to use?

• I'm not sure what you're asking, given that you immediately posted your own answer. Are you asking for us to check your calculation? If so, then the work should be included in the question not as an answer.
– BBS
Nov 7 '16 at 14:03
• @BBS I posted a self-answered question to help others. This is standard operating procedure on other SE sites; is it not here? Nov 7 '16 at 15:58
• Ok, I'm fine with that. I was just legitimately confused.
– BBS
Nov 7 '16 at 16:48
• @BBS if the question could be clarified please edit :D Nov 7 '16 at 16:50

## Determine gravity of honey

Combine a known volume V_w of water with a known volume of honey V_h. measure the gravity of the mixture and denote that quantity g_m. The gravity of the honey g_h is

g_h = (g_m (V_w + V_h) - V_w) / V_h.

For example, if you mix 1 gallon of honey with 2 gallons of water and measure a specific gravity of g_m = 1.14, then the specific gravity of the honey is

g_h = (1.14 (2gal + 1gal) - 2gal) / 1gal = 1.42.

## Volume of honey for target starting gravity

Given a target total must volume V_t, and target starting gravity g_s, the volume of honey V_h needed is

V_h = V_t (g_s - 1) / (g_h - 1).

For example, if we want V_t = 5 gallons total must volume with starting gravity g_s = 1.1, then the volume of honey we need is

V_h = 5gal (1.1 - 1) / (1.42 - 1) = 1.2gal.

• I follow the basic equations but shouldn't you be doing this by weight and not volume? Weight of water used and weight of honey used. Seems like that would be more accurate. Nov 7 '16 at 12:17
• I'm no chemist, but if you start and end with the same choice (volume or weight), it seems like it would work out the same.
– Dale
Nov 8 '16 at 22:12