expressions of residual sugar

Many times rs is expressed as a % age, and other times it is expressed in G/l. I am sure I knew in another life how to mentally convert one to the other, and I believe it is a simple decimal placement move. IOW, if a wine has 4.0 g/l rs, one simply moves the decimal point one position to the left and it is 0.4% rs. Thanks for any response.

Bob:

You are correct; 4 grams per liter = 0.4% residual sugar; 1000 grams = 1liter (but this depends on the temperature and the density of the liquid).

marco

Bob:

You are correct; 4 grams per liter = 0.4% residual sugar; 1000 grams = 1liter (but this depends on the temperature and the density of the liquid).

marco

Thanks Marco, I guess I remembered my previous life well enough!

Yes Bob, Marco and you are correct. However, from a home winemaker's viewpoint, I thought I'd add from my experience. If I want a wine to have sweetness when finished, it is difficult for a home wine maker to stop fermentation at a precise time, so I let it ferment out to bone dry and add cane sugar before bottling. I also don't have a scale, so after careful measurements, I've figured out that 1 cup of sugar, when added to 5 gallons of wine will yield almost exactly 1% rs in the finished wine. I seldom sweeten wines more that 1.5%.

The math works out Howie.
1 cup of sugar weighs approximately 200 g
5 gals of wine = 18.9 L
200 g / 18.9 L = 10.6 g / L = 1.06 %

Salute

I thought this was going to be another thread about the joys of classifying German sweet/off-dry wine!