good calculator for mixed batches

[hooch0325]

I want to combine two separately primary fermented batches in secondary and want to make sure I keep the abv calcs accurate. I've seen a formula before but can't find it (something like a weighted average ((og1 - fg1 * volume1)+ (og2 - fg2 * vol2))/(vol1+vol2). Also, is there a calculator anywhere that figures this out for you.

Thank you.

 

[brazedowl]

Well here's what I'd do...
1) Figure out the separate abvs (LINK)
2) Use that to get the total volume of alcohol in each batch.
3) Add those
4) Divide by the total volume of the two combined batches.

(ABV1 * VOL1) + (ABV2 * VOL2) = ALCVOLUME

ALCVOLUME / (VOL1 + VOL2) = COMBINED ABV

Make sure your abv is in a decimal before doing the math (10% = 0.1)

 

[saramc]

Great resource here... http://www.winebusiness.com/tools/