Beer %

RorieRorie Member Posts: 8

I am finding that my calculated beer % (taken from specific gravity) is alway lower than the beer should be. In general, i am finding that both my starting SG and my ending SG are lower than the instructions.

Most recent example is my Grand Cru, Original SG 1.046 and final 1.002 (5.7%). But the instructions state original 1.075 and final 1.01 (8.5%)

Why is this?


  • HBO_StaffHBO_Staff Administrator Posts: 2,115
    There can be a number of reasons for hydrometer readings not being as expected, and usually they are nothing to worry about as the strength will work out as the manufacturers state. The most important thing to make the alcohol content correct is to ensure that you add the right amount of additives - in this case spraymalt or sugar - and then top it up to the correct amount of liquid. If there is not enough sugars or too much liquid is added it will be weaker.

    Reading of the hydrometer will also account for some discrepancies as there is always some variation between people.

    Priming the brew in a barrel or bottles will also increase the strength, that priming sugar/drops will dissolve and secondary ferment and add to the alcohol content.

    Temperature can also be a factor and affect the readings, an allowance can be made for this if the hydrometer instructions state the correction needed.

    Looking at your readings the first one does sound on the low side, however this may not mean that anything was wrong, it may just be that the sugars had not fully dissolved when the reading was taken, they will dissolve though and ferment out, the low final gravity reading confirms that all the sugars are fermented.
  • BUDFORCEBUDFORCE Member Posts: 275
    I'm not convinced about the accuracy of those things anyway.

    They take a measurement of the weight if the liquid. So a sugary solution will weight more than water so your hydrometer doesn't drop as much. When it turns to sugar the liquid weighs less and also alcohol itself will weigh less than water.

    But... There are so many variables involved.

    They are good for measuring stability so to make sure fermentation has finished, but for accurate alcohol measurements I wouldn't bother. I don't use my hydrometer at all any more.
    Beer League: 1. Young's - American Pale Ale 2. Bulldog Brews - Imperial Red Bad Cat 3. Young's - IPA 4. Young's - American Amber Ale 5. Bulldog Brews - Evil Dog Double IPA
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