Mixing extracts with different EBC values?

[GavH]

Bone question perhaps, but:

If I take a kit of malt extract (ie Coopers) with an EBC value of (for talking sake) 530 and mix it with a can of Amber LME which has an EBC of 340, what is the eventual EBC rating?

Or is there no way to calculate it until the brew has been made?

 

[dennisking]

My gut instinct would be to add both values together an divide by 2 but is that to straightforward.

 

[simon04]

There are pieces of software that could help.

I use Brewtarget on Linux, but I'm not sure about Windows software,