Calculating Grain Requirements

[Sudz]

Question guys...

When changing the batch size of a recipe, I've always assumed that you just need to ratio the grain bill by the ratio change of the water. As an example, if you have a 10 lb grain requirement for a 5 gal batch size and want to brew 10 gal you would simply multiply the grain by the water ratio 10/5 or 2. This would give you 20lbs of grain required to brew 10 gal.

Is this logic correct?

The reason I ask is I keep finding recipes people have converted where this "philosophy" doesn't appear to add up. So I'm wondering if maybe there is more to this than I think.

Inquiring minds want to know...

 

[oceanselv]

It is a linear relationship if you double the amount of water and hold all of the other variables such as boil time, evaporation rate etc as constants. perhaps the recipes you saw changed the boil time or some other variable.

 

[smee44]

I am still rather new but it depends on who converted it. People convert size and to their systems efficiencies and losses. This can change quantities of both ingredients and water.

 

[IrregularPulse]

Should be Linear.
I just used Beersmith to scale a 1G batch with 1.42G Boil volume up to 10G with 10.42G Boil volume and it went from 2lbs of 2row at 1054 to 20lbs of 2row at 1054

People also convert for their systems efficiency however. Some people are as low as 60%, some maybe as high as 90%. This will alter the amount of grain needed. You need to figure out your efficiency.

 

[Sudz]

Thanks guys. Linear it is...

I failed to state all other variables remained the same. So just changing batch size is a simple ratio as I thought.

Thanks again for removing my cobwebs....