Formular or calculator for batch blending?

[onlooker]

I often blend batches of beer, sometimes they are two batches of the same recipe where I havent hit my target gravity so I brew again alittle stronger and blend them , and sometimes it is two totally different ales. A problem I have is that blending leaves me not being able to calculate alc since I dont have one og and one fg. Does anyone know of a formular where I can calculate this? or even better a web calculator that will do it for me (as Im no maths genius)?

[Andy]

Beersmith has a "Dilution calculator" where you can calculate the effect of adding either water or wort to another batch of wort. Exactly what you want by the sounds of it.

[onlooker]

Not really, I already have dilution tables. Im not diluting with water I am diluting with beer!! so the fluid that is being used to dilute has alc in it.

[steve_flack]

The principal is relatively simple as it's the same as a straight dilution

Points in these equations means (Og-1.000)x1000 (so 1.040 is 40 points)

Points in mixture = ((points in beer 1Xvolume 1)+(points in beer 2xvolume 2))/ Total Volume


ABV is much the same if you know both ABVs and both volumes.

[confused]

I'm not brill at these things either and couldn't do "equations" at school, certainly not going to deal with them now. Presuming you have two finished brews for which you know the ABV I dont see why you can't simply calulate the volume alcohol for each then divide the total back in to the total liquor, thus

25 litres at 4% yields 1 litre alcohol (25 x 4 / 100)
15 litres at 5.2% yields 0.78 litres alcohol (15 x 5.2 / 100)

40 litres with 1.78 litres alcohol equtes to 4.5% ABV (1.78 / 40)

If it's a case of blending part brewed worts then i think I'd be on ebay looking for a refactometer or whatever they are called

[steve_flack]

Refractometers aren't much help for fermented beers unless you know what the OG was.

[Andy]

Refractometers aren't much help for fermented beers unless you know what the OG was.

If use a refractometer in tandem with a good hydrometer on a fermented beer then you can work out what the OG was.

[onlooker]

I think thats alot of help, I have had a few pints and will have to look at it again in the morning, but cheers that should help.