Trouble with mash efficiency

[JGowls]

I did my first BIAB earlier today and am having trouble with figuring out my mash efficiency. I used 10 pounds of maris otter, My pre boil volume was 7 gallons with a 1.056 SG. My post boil volume was a little over 5 gallons with a 1.052 reading. Ive looked at different forum posts and things online and still cant figure out the efficiency. Can someone please help me figure out what efficiency I achieved? If its a low efficiency, itll just be a learning experience as I need to get dialed in on my new outdoor burner. The predicted efficiency was 82.4 on beersmith if that helps at all. Thanks in advance

 

[hopmonster2189]

You post boil gravity should always be higher than you pre boil if no water is added after the pre boil reading. MO (edit: 2 row base malt) has somewhere around 38 pts/lb/gal (How to Brew by John Palmer) if 100% efficiency is achieved, so your pre boil gravity should have been a max of 38 x 10 / 7 = 54.3 or 1.054, giving a post boil max gravity of 54.3 x 7 / 5 = 1.076. Was all the wort mixed well for your pre boil reading? Assuming your post boil reading was correct your pre boil would have been 1.037, so 37 / 54.3 = 68.3% efficiency. Hope this helps?

 

[JGowls]

My preboil reading may have been off, I didnt really mix the wort well enough before grabbing a sample. With the post boil reading, I may have not gotten it down all the way to 60* before taking a hydro sample. There were alot of problems with my brew day so it could have been for a number of reasons why the efficiency was so low. Thanks for the help again

 

[hopmonster2189]

Around 70% isn't bad at all, especially for just starting out