OG and Temperature

Ok guys, quick question. Made a summer brew about two weeks ago. OG was supposed to be 1.051 but it wound up being 1.046. I think I might have taken my OG when the wort was still a little warm. This was a partial mash brew.

My question is how much does heat affect your OG.

Here this should help: http://www.howtobrew.com/appendices/appendixA.html

If the wort was still warm and you did a partial boil (diluted with cold water) then it's possible the wort wasn't fully mixed when you took your reading giving you a slightly inaccurate reading. But getting 1.046 when you were expecting 1.051 isn't bad and I wouldn't lose any sleep, your beer will be just fine. Since you mention a partial mash it's possible you didn't get the full conversion you were expecting. I know my first mashes were only about 60% efficient until I refined my technique, now I'm consistently at 75%. Monitor your next few mashes closely (take a hydrometer reading from the kettle) to determine what your efficiency is. That'll help you plan recipes better (i.e.use a little more grain if your efficiency is low).

I've always enjoyed this calculator. Compensates for temps...and best of all, no math.

http://www.rooftopbrew.net/abv.php