VST Coffee Refractometer : whats the difference between BW (g) and BEV (g)

(Brian O'briain) #1

Hi All

Anyone able to help explain the difference between the brew weight BW and beverage BEV with immersion/drip?

I’m using the Iphone VST tool, and having read the manual, I’m still none the wiser :frowning2:


(Tom Bomford) #2

I got carried away and probably covered stuff you already know but there is a simple answer at the bottom if you can’t be bothered reading :+1:

BW is more specifically Brew Water Weight.
i.e. 15g coffee:250g Brew Water

The Beverage Weight is simply the total weight of your brewed coffee. Which usually sits somewhere between 205-220g with the above ratio (for me).

When using the app you’ll find that neither of these variables can be adjusted without affecting the other as the app maintains a specific ratio between their values.
So as you drag one across, the other will change as well.

The Liquid Retention Ratio (LRR) is the value that determines how far apart they are.
It’s essentially deciding how much water was retained in the bed of coffee based off the numbers you’ve given it.
You should see it in a small box next to Moisture and Co2 etc.

This is a number that I adjust frequently so my BW and my Bev values in the app reflect my actual brew.

So when I drag the brew water across to 250g, it may automatically decide my beverage weight is 205g when I actually got 215g out.

By lowering the LRR value I’m letting the app know that less water has been retained in my bed and therefore my beverage weight was larger (215).
This ratio matters because the EXT% is calculated using the TDS% of your beverage weight not your brew water weight.

If you click into Presets, then Settings, you’ll find that you can adjust the LRR for both drip and immersion.

So simply:
Brew Water Weight = how much water went in.
Beverage Weight = how much brewed coffee came out.
LRR = the difference (as a ratio) between BW and Bev.

Hope this helps in some way.

(Brian O'briain) #3

Hi Tom
Thanks so much for your detailed response.
It absolutely makes sense now.
Much obliged buddy
Regards Brian

(Dalton Greene) #4

How accurate do you get the LRR in immersion brews? When I make an aeropress or similar, I purposefully do not press too much towards the end of the brew to avoid unwanted bits and cloudiness seeping in.
I am quite unsure of the actual LRR compared to drip brews.
Nice explanation by the way, very clear for people to understand.

(Matthew Perger) #5

LRR in immersion is redundant because you input the brew water.

For drip, always measure the beverage weight, and for immersion always measure the brew water. This way you’ll never need to worry about setting the LRR!

(Firdaus Omar) #6


Great discussion on the VST! I have one question today that has been bugging me for several days; there’s a parameter called “Spent” measured in weight (grams) listed under the measure header in the VST Coffee Pro Tools.

Can anyone help me understand what does it actually measure? I’ve been trying several possibilities but to know avail.

Thank you!


(Tom Bomford) #7

You’ve just saved me so much time mate :+1:

(Prince tarausai ) #8

I love this discussion just out of interest the brew tool youbtaking about,is it free download on your App Store ?