How much dry yeast to use?

I am preparing to brew a loose cannon clone.OG will be 1.075.I will be using US-05.Will one packet be enough,or should I use 2? T.I.A.

I've brewed OGs pretty similar with one packet. Rehydrating should help keep your full cell count if your concerned.

Dry yeast has about 20b cells per gram. So 11.5g x 20b = 230b. If properly rehydrated, 90% of those should be viable. 230b x 0.9 = 207b.

"Rule of thumb" pitching rate for ales is 0.75m yeast cells per batch size in ml per degree Plato. So, what's your batch size?

Batch size will be 5.5 gallons.

So, if you plug in the numbers, you'll get 750,000 x 20,820 x 18 = 281,070,000,000 or ~ 281b cells, meaning one pack will be 74b short (about 25% less than recommended). Can you get away with that? Probably, but make sure you aerate well, and I'd use yeast nutrient if you have it. If you don't properly rehydrate your yeast, only about 50% of them will be viable, in which case you'd be seriously underpitching.

Nateo said:

So, if you plug in the numbers, you'll get 750,000 x 20,820 x 18 = 281,070,000,000 or ~ 281b cells, meaning one pack will be 74b short (about 25% less than recommended). Can you get away with that? Probably, but make sure you aerate well, and I'd use yeast nutrient if you have it. If you don't properly rehydrate your yeast, only about 50% of them will be viable, in which case you'd be seriously underpitching.

Click to expand...

Actually,I have 2 packets on hand.I will pitch them both. Thanks a bunch for the replies.I have brewed solely with liquid yeast since day one. I am new to dry yeast as this is only my second batch using it. Thanks again

When I started brewing, I only used liquid yeast. Now I almost only use dry yeast. I've only really had good luck with the Fermentis brand dry yeast, so that's all I'll use. Dry is cheaper, you get twice as much yeast vs a smack pack or vial, and it mails really well. I live in the boonies and do almost all my homebrew shopping online now.

Nateo said:

When I started brewing, I only used liquid yeast. Now I almost only use dry yeast. I've only really had good luck with the Fermentis brand dry yeast, so that's all I'll use. Dry is cheaper, you get twice as much yeast vs a smack pack or vial, and it mails really well. I live in the boonies and do almost all my homebrew shopping online now.

Click to expand...

Your situation sounds very similar to mine.

The "standard" pitching rate is 1m/ml/*P, and lots of people recommend scaling down a bit for ales (0.75m) and scaling up a bit for lagers (1.5m). So 1000000 x 20820 x 18 = 375b. So two properly rehydrated packs isn't too crazy, and would probably be better than underpitching.

How I rehydrate - with about 30 minutes left in the boil, get a small mason jar. You can fill by weight or volume, but you want 10x the weight of the yeast in water. So for 11.5g I'll fill the jar with ~ 120g / 120ml. Nuke it for 3min or so, so it can boil for a bit. I'll leave it in the microwave until it cools down, then once the boil is almost done, I'll throw the yeast in the jar. Agitate it a little bit so it doesn't all just clump together. Let that stand 15min or so, while you're chilling your wort. Once the wort is chilled, you can pitch the yeast.

For bigger beers (like 1.070+), you should really use a blow-off tube, just to be safe. The dry yeast takes off really quickly if you rehydrate it properly.