When calculating Final Gravity (FG), what should FG generally be in relation to Original Gravity (OG)?

Final Gravity (FG) is a crucial measurement in brewing that indicates the specific gravity of the beer after fermentation has completed. In relation to Original Gravity (OG), FG generally represents the amount of unfermented sugars left in the beer, which is measured after the fermentation process.

The correct understanding of the relationship between FG and OG is that FG should typically be lower than OG, reflecting the conversion of sugars into alcohol and carbon dioxide during fermentation. The final gravity can vary depending on the style of beer, yeast used, fermentation conditions, and the residual sugars remaining.

Generally, a value like 1/4 of the OG would imply a significant amount of sugar has been fermented, which in most cases does not accurately represent the relationship, as the FG typically ranges from about a bit higher than half to a little lower than the OG, depending on the fermentation characteristics.

Therefore, it’s important to note that while FG does decrease compared to OG, the volume of OG isn’t usually expressed as a fraction like 1/4 or 1/8. A more typical range might put FG above 1.010 for many styles, reflecting either a dry or balanced beer depending on the additional ingredients and the attenuation of the yeast.