What volume of sparge water to use? First all-grain

I'm just starting my first all-grain right now, woo! I'm doing a half recipe and using the easy stovetop all-grain thread as a guide. Anyway, my mash is going right now and I hit my target temp perfectly. Now I'm wondering how much strike water to use.

Here's what info I can give. 5 lbs of grain is mashing in 1.25 gallons of water currently. Now that it's cut in half, the batch size will be 2.5 gallons. The normal recipe calls for a 3 gallon boil, but I honestly don't know how this should be altered.

Basically what I need to know is how much sparge what I need to use, and what my boil volume should be. Thanks.

Easy, you'll get about .75 gallons out of the mash when you remove that grain bag. Dunk that bag into a pot with 2.5 gallons of "sparge" water. You'll start boiling 3.25 gallons and boil down to just over 2.5 after 60 minutes... probably.

Thanks for the timely reply! I followed your instructions and everything seemed to work well. My wort is cooling and I'm about to pitch onto a yeast cake for the first time. Anyway, now that I have the answers I needed, can anyone explain how I can calculate them myself next time?

Gtrman13 said:

Thanks for the timely reply! I followed your instructions and everything seemed to work well. My wort is cooling and I'm about to pitch onto a yeast cake for the first time. Anyway, now that I have the answers I needed, can anyone explain how I can calculate them myself next time?

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You can count on ~0.1 gallons per pound of grain lost to absorbtion (you had 5 lbs of grain and 1.25 gallons water to start - so .5 gallons lost = 0.75 gallons after the mash).

You're loss during the boil will depend on your boil intensity (I usually plan for ~1 gallon/hour)