Calibrating my Hydrometer

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TexasSpartan

Well-Known Member
I'm just an extract brewer, and my OG and FG readings are always a little off. Never enough that I feel the need to ask if I've ruined my beer, but they're not what they should be.

I checked my hydrometer, and it says it is calibrated for 60 degrees. Look, I live in Texas. My house is never 60 degrees. The kitchen is usually closer to 70-75 when I'm brewing. And more importantly, my beer is usually at 70 or so when I'm pitching the yeast or taking a reading for the FG. So how do I adjust for temperature?

My thought was this, and please correct me if I'm wrong. Get some distilled water and let it warm up to room temperature. Drop the hydrometer and see what it reads. At 60 degrees it should read 1.000, correct? So if it read 0.998 (for example) at 70 degrees, I would add 0.002 to whatever reading I got.

Am I on the right track, or way off base?

Nugu

Well-Known Member
There's an equation you can plug it into I think. Unfortunately I don't know it (undoubtedly someone will enlighten us though) but ya that would work assuming you always took the reading at 70F.

I generally leave close enough as close enough. (we're talking it being off at most like .002

david_42

Well-Known Member
The correction varies with temperature and gravity, but the simplest thing it to check your hydrometer a 60F, then at 70F. Shouldn't be more than 0.002 delta.

McKBrew

Well-Known Member
There are several free applications on the internet that will do the conversion for you.

eljefebrewing

Well-Known Member
Look in Appendix I (I think) on howtobrew.com. Nice table there.

bull8042

I like 'em shaved
Lifetime Supporter
BeerSmith also has a correction tool that requires you to enter the temp of the sample and the reading and it will give the corrected value.

shawnbou

Zyme Lord
Lifetime Supporter
I'm very new to this myself, but as a fellow Texan I can relate to your problems getting your house down to 60F!

My hydrometer reads accurately at 68F, so I think it may just vary from one hydrometer to another. Mine did come with a handy chart, though, for corrections due to temperature. I add .001 for every 9 degrees over 68, and subtract .001 for every 9 degrees under 68 ... the concept here being that warmer liquids are thinner and therefore will have a higher SG when they get to room temp, and vice versa.

Hope that helps. It sounds like you're on the right track.