Hi

Sorry if this has been asked already, but after scouring brewing websites for days and getting multiple headaches, I'm still no nearer find the answer to the question;

How do I calculate gravity using metric rather than US units?

I've read plenty of things that use the US units, for example;

*A rule of thumb is one pound of liquid extract per gallon of water for a light bodied beer. One and a half pounds per gallon produces a richer, full bodied beer. A pound of LME typically yields a gravity of 1.034 - 38, as measured by a hydrometer, when dissolved in one gallon of water. DME yields about 1.040 - 43. These yield values are referred to as Points per Pound per Gallon. If someone tells you that a certain extract or malt's yield is 36 points, it means that when 1 pound is dissolved into 1 gallon of water, the gravity is 1.036. If that 1 pound is dissolved into 3 gallons, its gravity would be 36/3 = 12 or 1.012. The gravity is how the strength of a beer is described. Most commercial beers have an Original Gravity (OG) of 1.035 - 1.050.*

**Example of Gravity Calculations**

If you want to brew 5 gallons of 1.040 gravity beer, this would call for 5 lbs of DME having 40 pts/lb./gal, or 5.5 lbs of LME having 36 pts/lb./gal.

i.e. 1.040 = 40 pts/gal x 5 gal = 200 pts total

200 pts = 36 pts/lb. x (?) lbs => (?) lbs = 200 / 36 = 5.55 lbs.

5.55 lb. of 36 pts/lb./gal LME are needed to make the same 5 gallons of beer.

Note: The same concept can be used with the SI units of Liter Degrees per Kilogram, i.e., L°/kg or pts./kg/L. The conversion factor between ppg and L°/kg is 8.3454 x ppg = L°/kg.

The above makes sense, however I need to work in metric units. The underlined note above states the concept can work in metric and even gives the factor to convert between ppg and L°/kg (ppg x 8.3454), however I can't find anything that will help me work everything out in metric. i.e.;

1.040 = ??? pts/L x 20L = ??? pts total

??? pts = ??? pts/kg x (?) kg =. (?) kg = ??? / ??? = ??? kg

??? kg of ??? pts/kg/L LME are needed to make the same 20 litres of beer.

Does any of this make sense??? I've been going round in circles with this for days and now my head is so scrambled I'm not sure I could even find my way out of the front door.