# Complex Formula

• Jan 25th 2013, 10:53 AM
happyapple
Complex Formula
Hello Math Wizards. Can someone help me with the following formula?

ABV = (76.08 * (OG-FG) / (1.775-OG)) * (FG / 0.794)

Obviously, it assumes the user knows the value of OG and FG, and wishes to solve for ABV.

Can someone rewrite this formula for me to solve for OG, assuming the user knows the value of ABV and FG?

Thank you.
• Jan 25th 2013, 11:39 AM
ebaines
Re: Complex Formula
Assuming the equation you meant is this:

$\displaystyle ABV = \frac {76.08(OG-FG)}{(1.775 - OG)} \times \frac {FG}{0.794}$,

then:

$\displaystyle OG = \frac {(1.775 AVG + 95.819 FG^2)}{(95.819 + AVG)}$
• Jan 25th 2013, 12:20 PM
happyapple
Re: Complex Formula
Hi ebaines. Thanks. Yes, that is the equation I meant. But when I try to solve for OG using your formula, I'm not getting the expected result.

For example, for testing's sake, if I solve for ABV using these values:

OG = 1.052
FG = 1.012

then I get ABV = 5.3648

However, if I use your formula to work the problem backwards, and solve instead for OG, I don't get the correct answer.

OG should equal 1.052 in your formula, but it does not. Any help?

Thanks.
• Jan 25th 2013, 01:11 PM
ebaines
Re: Complex Formula
Keyboard error, sorry. I left an FG term out of the denominator. Correct answer is:

$\displaystyle OG = \frac {(1.775 AVG + 95.819 FG^2)}{(95.819FG + AVG)}$
• Jan 25th 2013, 01:23 PM
happyapple
Re: Complex Formula
Perfect. Thank you again.