Can somebody help with these bottles?

[FunkedOut]

I recently got larger fermenters, so I want to make enough brew to fill a keg and a 1L bottle or two.
I’m fermenting in keg, so I can make use of a spunding valve and capture some natural carbonation.
The beer is always settled at 15psi before cold crash and drops to about 5psi after.

5psi @ 32*F = 2.15 volumes.
How do I go about calculating the amount of sugar I need to get another 0.35 volumes?
Is it as easy as telling Beersmith I want 0.35 volumes of CO2?

Thanks.

 

[jalc6927]

Maybe fill the bottle using carb drops or sugar directly in bottle then proceed with the keg as you normally would

 

[FunkedOut]

According to braukaiser, the formula/calculation for priming sugar is:

Cbeer = Cflat-beer + 0.5 * 0.91 * mcorn-sugar / Vbeer

• Cbeer - the final carbonation of the beer (g/l)
• Cflat-beer - the CO2 content of the beer before bottling (g/l)
• mcorn-sugar - the weight of the corn sugar (glucose monohydrate) (g)
• Vbeer - beer volume (l)

source:
http://braukaiser.com/wiki/index.php/Accurately_Calculating_Sugar_Additions_for_Carbonation


All of the bottling calculators I have found (including the Beersmith tool) use a temperature input value to calculate Cflat-beer in an effort to simplify the process.

After a couple to a few weeks of fermentation capped at 15psi, a rise to d-rest also capped at 15psi will eliminate some dissolved CO2.
A cold crash to 32*F (also capped at 15psi) will yield approximately 5psi. This pressure is maintained for a week after cold crash, I can then safely assume 2.15 volumes of CO2.
No need for a calculator to calculate the value of Cflat-beer.

Subtracting Cflat-beer from Cbeer will yield a difference that can be used to calculate the appropriate amount of priming sugar, using the formula above.
Something like this:

Cdelta = 0.5 * 0.91 * mcorn-sugar / Vbeer
​

So, my instinct was right in my OP about a simple subtraction being key, however, after learning more about priming calculators (including the Beersmith tool), I know that they are more more complicated and are not well suited for this particular calculation.
Luckily, the equation is simple, so a simple calculator will do just fine.

 

[FunkedOut]

Maybe fill the bottle using carb drops or sugar directly in bottle then proceed with the keg as you normally would

That is the basic plan, only I plan to use table sugar and want to know how much.
I fear that a carb drop would be way too much considering I’m almost there right at the start.