Lactic acid SG, sour mash and ABV

So you see me coming with the title...

I'm sure most people take the after boil OG and the FG to calculate the ABV %, but my logic says to me that the formulas that are used in calculating the alcool consider that an OG of 1.xxx is water at 1.000, and the remaining being mainly sugar.

That said, after a sour mash, there's another content, lactic acid, that have I guess, a different SG than water and sugar, so the formula doesn't exactly apply, right?

Or is the error margin so small that we doesn't bother?

Yes, it makes a difference. From what I understand, Lactic acid is heavier than water, so with the FG is actually higher for the amount of alcohol that is the beer.

For BW, I really don't take much notice of it. I make it a small beer (1.030-1.036) with the intent that it is more of an aperitif rather than a serious drink. I really do like a BW or other sour beer early in the evening, or with a meal.

Calder said:

Yes, it makes a difference. From what I understand, Lactic acid is heavier than water, so with the FG is actually higher for the amount of alcohol that is the beer.

For BW, I really don't take much notice of it. I make it a small beer (1.030-1.036) with the intent that it is more of an aperitif rather than a serious drink. I really do like a BW or other sour beer early in the evening, or with a meal.

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Yhea.. I did a BW and didn't really care about the ABV.. I just did everything to keep it as low as possible. But I'm asking the question now because I'm thinking to do a higher gravity sour mash, like a 1050 Raspberry wheat or a 1065 pseudo Oud Bruin.