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Est Original Gravity vs Est Pre-Boil Gravity

KB

Master Brewer
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I'm entering existing recipes into BeerSmith.

When I add or modify grain amounts I see both the Est Original Gravity and the Est Pre-Boil Gravity amounts change. These amounts are not the same values.

What are the differences between Est Original Gravity vs Est Pre-Boil Gravity?

Thanks.
 
The estimated pre-boil gravity is the gravity of the wort before the boil.

The estimated Original gravity is the gravity of the wort which goes into the fermentor (post-boil).

These are the target values calculated by BeerSmith in response to your grain bill (which is why it changes as you change malts and amounts) and your brew house (or total) efficiency which breaks down to your process losses (mash tun dead space, loss to trub and chilling) and mash efficiency.
 
The gravity of the wort will increase from the pre-boil gravity as water evaporates during the boil and the volume decreases. That gives a higher OG in the fermentor than the pre-boil gravity. If you do a partial boil and add top-up water in the fermentor, then you will be lowering the gravity again, so the OG at the start of fermentation may be lower than the pre-boil gravity (depends on the amount of top-up).

 
OK. Thanks. I need to remember the following.

On the left hand side, under "Style Guide Comparison" are the post boil numbers.

Toward the right hand side, under "Select Fields - Choose Fields" are the pre boil numbers.
 
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