How much strike water?

Howdy all!  Brand new to BIAB brewing, so I’m hoping this forum is ok to post to.  I’m brewing my first batch of BIAB.  It’s a blonde, and I plan to add blueberry extract to the keg stage after fermentation.  Here is what I have -

8lbs. Of 2 Row Premium Malt
1oz of Mt. Hood Hops
US-05 yeast

I plan to use 6.5 gallons of strike water, but I’m working with an 8 gallon brew kettle.

Any thoughts?  Thanks!

I assume you are worried about space in your kettle? 8# of grain should displace about a gallon of water and absorb about .8 gallons so you should have enough room.

Excellent, thanks Pete!  If I don’t, I’m assuming my end product going to fermentation will be smaller, how will this affect OG?

I actually do a “dunk sparge” when doing biab. I use 1.5 quarts of water per pound of grain as my strike water. The remaining water I put in a separate kettle. While mashing I heat the rest of the water to about 175 and when I’m done mashing I pull the bag, drain over the mash kettle, then transfer to the other. I move that around a bit, drain bag again, and combine contents of both kettles for the boil. That gives you extra room and IME, just a bit better efficiency.

Ok great, I can give that a shot!  Thanks  again!!