Preparing starter wort is much easier using the metric system than it is using Americanized English units of measurement. The most common starter wort specific gravity is 1.040. Wort is a solution. A solution is composed of a solute (DME) and a solvent (water). A wort with a specific gravity of 1.040 is a 10% weight by volume (w/v) solution. The letter to the left of the slash is the solute measurement. The letter to right of the slash is the solvent measurement.

Professional brewers use degrees Plato. Degrees Plato tells us what percentage of a batch of wort is sugar by weight because degrees Plato is a weight by weight (w/w) unit of measurement. The beauty of using the metric system is that 1 milliliter of water weighs 1 gram; hence, w/w = w/v when the solvent is water.

Examples

A 1L 1.040 Starter (10% w/v solution)

1000ml * 0.1 = 100g of DME

in w/v terms, 100g/1000ml

We can make a starter of any specific gravity (SG) by converting SG to degrees Plato. The American Society of Brewing Chemists (ASBC) polynomial for converting SG to degrees Plato is:

Degrees Plato = 616.868 + 1111.14 * SG - 630.272 * SG

^{2} + 135.997 * SG

^{3}That's way too much like work to perform by hand. We can either automate the calculation using software, or we can just use a look-up table such as the one at this URL:

http://www.brewersfriend.com/plato-to-sg-conversion-chart/1.065 S.G. = 16P or 16% w/w, which is 16% w/v when the solvent is water

A 1L 1.065 Starter

1000ml * 0.16 = 160g of DME

in w/v terms, 160g/1000ml