Need help currently brew in progress. How to determine FG with boil down

First all grain brew. My goal is 2.5gallons for primary with SG of 1.100. After my mash I had 4.5 gallons of wort. First question is what volume do I have to boil down to to reach my desired SG? If it's more or less then 2.5 gallons them im ok with that. Next question is on average how long will it take to boil down to that volume or even better at what volume should I start my 60 minute hop addition?

To help we need to know a gravity reading and temperature right now. Else we do not know how much to boil off to hit your target gravity or if you can even make it.

Send it and I can do the math quickly.

Sorry, forgot to post that. After mashing my SG was 1.061 PH 5.40 volume 4.5

To get to 1.100 you will have to boil off 1.64 gallons....but... that leaves you with 2.75 gallons I think. Or to get to 2.5 gallons you will end up with 1.110 wort.

It is impossible for me to calculate your boil off rate or know it so I would recommend starting the boil and trying to calculate your boil off rate using the first 30 minutes of boil time.

I would guess at a minimum you are looking at 90 minutes of boiling based upon your numbers. More likely you are going to need 115 minutes plus I would guess so you should have plenty of time to calculate your boil off then stage the hop additions in the last 60 minutes.

You should invest in some brewing software. It will help you make these calculations and help with recipe volumes.

If you need more help just ask or PM me.

Thanks for the help.
I will shoot for 2.75 gallons. I have beersmith but obviously need to do a little studying on all grain....used it for my last 12 extract brews and this is my first all grain. I also missed my mash in temp so had to add additional water to bring it up so that also messed with my plans. So far it's boiling away slowly...probably .25g every half an hour

In BeerSmith go to tools then click on boil off tool.

Here you can play with the various outcomes you can have based on the starting volume. More beer correct gravity, correct volume, wrong gravity.

Also since you are having some issues take a look at the dilution tool. Knowing that is there may help you in the future some day.

Cheers

SG ended up at 1.090...that's with a 2l starter so sounds pretty good to me. Total volume was about 2.8 gallons. Thanks for the help!

Cool. Let me know how it turns out!

strongarm said:

SG ended up at 1.090...that's with a 2l starter so sounds pretty good to me. Total volume was about 2.8 gallons. Thanks for the help!

Click to expand...

Next time cold crash the starter for 24 hours and decant the spent starter wort. That way you're just pouring in the yeast slurry. There's plenty of threads/posts about doing this.

I would have but was in a time crunch. Also it's a decent sized stout so I think the starter profile will get swollowed up by the beer.