Calculating Gallons of Grape Must from Pounds?

Does anyone have any idea how to calculate the number of gallons I have from the weight of must (crushed grapes)? Would it be close to just divide by 8.34 (water)? Calculations for adding yeast, nutrients, etc are all given for gallons but when my fermenters are filled by weight and I've been mostly guessing at the number of gallons so far.

Thanks in advance.

[JohnS]

Originally Posted by Unregistered

Does anyone have any idea how to calculate the number of gallons I have from the weight of must (crushed grapes)? Would it be close to just divide by 8.34 (water)? Calculations for adding yeast, nutrients, etc are all given for gallons but when my fermenters are filled by weight and I've been mostly guessing at the number of gallons so far.

Thanks in advance.

Using the value for water would be gairly close.

I believe the sugar content would make it slightly higher. A hydrometer is a relatively inexpensive glass float (about $20) for measuring density or specific gravity. If SG were 1.05, the weight per gallon would be 5% higher than water, 8.76 lb/gallon.

I would suggest researching typical starting SG on the Internet or buying a hydrometer. As the sugars are fermented, the SG will fall to a value close to 1.00 or a little below. Thus SG is used to monitor fermentation throughout the process.

Note that hydrometers which are sensitive (give high resolution readings) have a relatively narrow range. Do some research to determine range most relevant to wine-making.

Do you have an empty fermenter? Fill it with water and weight (weigh empty first). Use a dipstick to measure depth, and weight to establish gallons. Make a table. If your other fermenters are the same size (nominally) they will all be close)

Thanks for the great advice! I do have a hydrometer the complication at this point is getting enough liquid from the must to fill my graduated cylinder. If I can't get enough liquid I will try the water method. Thanks again!