Adding sugar, how to calculate

I’m trying to figure out how to calculate ABV when staggering additional sugar during fermentation (to keep the ferment going longer and get a higher ABV).

Can I just add it up?

For example, assume my batch started at 1.060
A few days later it’s at 1.030 and I add sugar to bring it back up to 1.060
Assuming it finishes at 1.020, can I add the extra 0.030 to my original gravity and calculate it as 1.090 - 1.020 x 131 to get a correct ABV, or does the math no longer work since I messed with the process?

Yes you can just add up the total of all the additions the math should not change.


1lb of sugar adds ~1.009 gravity points to 5 gallons. Keep track of how much sugar you add and you will not need to take multiple hydrometer readings.

Also, trying to get an accurate reading after adding the sugar will be next to impossible. 1st you have to get it dissolved, then mixed thoroughly. But after a couple of hours it should dissolve, and then the yeast will find it.