My first homebrew has a very low alcohol content

Question

I just finished my first homebrew (yay!), but my hydrometer is reading a very low alcohol content. I brewed an Edme bitter (pre-made wort and I bought the malt extract) and it tastes great, but it's only reading about 1% alcohol content. I have a floating-style hydrometer that came with my brewing kit.

I basically had it in the primary for about 5 days, then in the carboy for another 11-12 days. Then I added my corn dextrose (I believe that's what its called) for carbonation and bottled it in PET bottles. I left it in the bottle about 2 weeks and just started drinking it now.

What did I do wrong to have such a low alcohol content? Did I not leave it to ferment long enough?

Answer 1

Your process sounds fine - it's the way you're using the hydrometer that's the problem.

To estimate alcohol content, you need to take a reading at the start of fermentation. You cannot read the alcohol content from the hydrometer alcohol scale at the end of fermentation.

The hydrometer cannot measure the alcohol content directly, but it can estimate how much alcohol may be produced from the sugars available at the start of fermentation. That's why you take a gravity reading before fermentation starts.

If you have a original gravity reading, there's a alcohol content calculator that you can use - just plug in your gravity readings at the start and end of fermentation and it computes the alcohol content.

For example, a beer with original gravity of 1.040 and final gravity of 1.010 has an alcohol content of 3.9 percent.