Step 11: Optional: Measure Gravity
A hydrometer allows you to measure the starting gravity of your wort. Using the Original Gravity (OG) and Final Gravity (FG) you will be able to calculate the alcohol content of your beer.
Knowing the OG and FG also allows you to know when fermentation is complete and your beer is ready to rack for bottling.
This wort has an OG of 1.084 which is right on target for an Imperial Stout.