ABV

[WallyBrew]

The P stands for present

In determining the original gravity by distillation you determine:

The present gravity (beer after filtration) you're calling it FG

The extract gravity - the bit left after distillation and made back to the original volume by dilution with distilled water.

And the gravity of the distillate

The difference between the distillate gravity say 992.8 and 1000 = 7.2 is known as the degrees of spirit and by looking this figure up in the appropriate tables (originally due to Thorpe) you obtain the degrees of gravity that have been lost. Add this to the extract gravity and you get the OG

If you want a worked example !!!

[steve_flack]

Bugger! I must have spent an hour looking for that.

Obviously my well trained google skills came to the fore there....also I was pretty certain I'd seen it in the big whopping Beer Duty document on the C&E website.

[edit1now]

Could we get some of this on as a Sticky please?

[Farmer Woosnip]

I know this has probably been asked a million times before but I can't find it (Haven't looked that hard to be honest)...

What about the extra bit for secondary fermentation in the bottle?

My Coopers kit suggests ((FG-OG)/7.46)+0.5

The 0.5 being to account for fermenting in the bottle.

Does that sound about right?

I promise I'll stop asking daft questions and digging up topics from 2008 once I've done this a few times.... still on my first kit at the moment and I want to know everything about everything.