Specific Gravity is an important measure for how to make beer. This measurement lets you know when your beer has completed fermentation, as well as how efficient fermentation was. You will be able to know how much of the available sugars were converted to alcohol. Gravity readings are taken using a hydrometer, which measures the density of liquids. A hydrometer floats higher the more dense a liquid is, and the reading of a liquid's density is expressed by the metric measurement called Specific Gravity.
Specific Gravity (SG) is the ratio of the density of a particular liquid in comparison to the density of water. Hydrometer readings taken just prior to fermentation are called Original Gravity (OG), and the targeted Specific Gravity of the beer is called the Final Gravity (FG). These numbers vary and depend upon what strain of yeast was used, as well as the type of beer that is being brewed. From all of these numbers the home brewer can determine alcohol percentage as well as the efficiency of the brewing process.
You should take hydrometer readings towards the end of fermentation, as this is the only certain way to determine when fermentation has completed. Do not rely only on visual cues. If you have a few consecutive days of the same Specific Gravity, then fermentation has completed. Make sure that your SG readings are within 5 points of your targeted Final Gravity. If your Specific Gravity is off by more than that, this indicates you have a stuck fermentation, and there are certain steps you must take to get the fermentation going again so that it will complete the process.
When you take hydrometer readings, it is important to make sure that oxygen does not get into your beer. You want to be careful that you do not splash or agitate the beer. All equipment that you use to take the hydrometer reading must first be sanitized, and sanitizing your hands is a good idea as well.
You can purchase a Wine Thief for taking samples for readings, or you could use a siphon that comes with most kits. Or, just use something that most people have lying around the house already--a turkey baster. Once you have drawn the sample, quickly reseal the fermenter to keep air out. Do not return the sample to the fermenter. You can either dump it, or taste it.
However, keep in mind that this is beer that is nowhere near ready yet, so do not panic if it doesn't taste too good. A quick way to determine what your final gravity should be is to take the Original Gravity before pitching the yeast. Take the number to the right of the decimal point and divide by 4.
For example, an OG of 1.060. Take 60 and divide by 4 = 15. Therefore, the Final Gravity should be 1.015.
In order to determine Alcohol By Volume (ABV), simply subtract the Final Gravity from the Original Gravity, and multiply by 131.
So, using the prior example, 1.060 - 1.015 = .045 X 131 = 5.9% ABV.
Specific Gravity (SG) is the ratio of the density of a particular liquid in comparison to the density of water. Hydrometer readings taken just prior to fermentation are called Original Gravity (OG), and the targeted Specific Gravity of the beer is called the Final Gravity (FG). These numbers vary and depend upon what strain of yeast was used, as well as the type of beer that is being brewed. From all of these numbers the home brewer can determine alcohol percentage as well as the efficiency of the brewing process.
You should take hydrometer readings towards the end of fermentation, as this is the only certain way to determine when fermentation has completed. Do not rely only on visual cues. If you have a few consecutive days of the same Specific Gravity, then fermentation has completed. Make sure that your SG readings are within 5 points of your targeted Final Gravity. If your Specific Gravity is off by more than that, this indicates you have a stuck fermentation, and there are certain steps you must take to get the fermentation going again so that it will complete the process.
When you take hydrometer readings, it is important to make sure that oxygen does not get into your beer. You want to be careful that you do not splash or agitate the beer. All equipment that you use to take the hydrometer reading must first be sanitized, and sanitizing your hands is a good idea as well.
You can purchase a Wine Thief for taking samples for readings, or you could use a siphon that comes with most kits. Or, just use something that most people have lying around the house already--a turkey baster. Once you have drawn the sample, quickly reseal the fermenter to keep air out. Do not return the sample to the fermenter. You can either dump it, or taste it.
However, keep in mind that this is beer that is nowhere near ready yet, so do not panic if it doesn't taste too good. A quick way to determine what your final gravity should be is to take the Original Gravity before pitching the yeast. Take the number to the right of the decimal point and divide by 4.
For example, an OG of 1.060. Take 60 and divide by 4 = 15. Therefore, the Final Gravity should be 1.015.
In order to determine Alcohol By Volume (ABV), simply subtract the Final Gravity from the Original Gravity, and multiply by 131.
So, using the prior example, 1.060 - 1.015 = .045 X 131 = 5.9% ABV.