So 2.6 to 3.5 ounces of light DME in .26 gallons of water lol.
I've got a scale that does grams (use it for my brewing salts additions to my water) and I'm also very comfortable with the metric system and conversions. Really though this was very informative thanks!
The problem with U.S. customary units is that a fluid ounce weighs 1.04 dry ounces (the reason why a gallon of water, 128 fluid ounces, weighs 8.33 pounds instead of 8 pounds). That is a clear cut example of how one cannot fix stupid, but these units have been with us pretty much since we were British colonies. The beauty of the metric system is that one milliliter of water weighs one gram. This relationship makes mixing weight by volume (w/v) solutions dead simple when the solvent is water. A 5% w/v solution has a specific gravity of 1.020 whereas 10% w/v solution has specific gravity of approximately 1.040 (it is very close). Degrees Plato is a said to be a weight by weight measurement system, but is actually weight by volume when using the metric system and the solvent is water. This relationship makes the number before the percent sign the gravity of the solution in degrees Plato (i.e., a 5% w/v solution is 5P and a 5P wort has a specific gravity of 1.020). Eric gave us an example of using w/v to make starter wort. Ten grams of DME in a 100ml solution is a 10% w/v solution. A 10% w/v solution has an S.G. of 1.040. The simple way to make a starter is to mix a 100 grams of DME into a little over 1L of water to allow for evaporation during the short pasteurizing boil. The goal is to have 100 grams of DME dissolved in a 1L solution after the starter wort is cooled, which is 10% w/v or an S.G. of 1.040.
The area where most Americans get hung up with the metric system is that they think in U.S. customary units and then translate to the metric system and vice versa. It is common to work this way at first. However, like learning a foreign language where one eventually starts to think in the foreign language instead of going through the translation step, one eventually reaches a point where one thinks in metric and measures in metric, no translation needed. That is the point where one realizes the disjointedness of the U.S. customary units of measure. A lot people will claim that we use imperial units, but that is not exactly correct. We use a modified version of imperial units of measure that leaves us on an island alone. A prime example is that an English (imperial) pint is 20 imperial fluid ounces, not 20 U.S. fluid ounces. An imperial pint is actually only 19.2 U.S. fluid ounces, some food for thought...