There are two ways to measure acidity. breastratable acidity is usually expressed as grams per liter, and is fairly easy to measure with an inexpensive breastration kit (using phenolphthalein indicator, and a standardized solution of sodium hydroxide). In the US and Canada, this is generally measured as if all the acids in the wine were tartaric acid. Typical values for a dry red would be from 6 to 7 g-l (or 0.60 to 0.70% acid).
The other way to measure acidity is pH. This requires a pH meter of some sort, and can be a bit more confusing, as the pH scale is logarithmic (not linear) and is affected by temperature and other chemicals in the must or wine. A lot of serious amateur winemakers end up with a pH meter (as well as acid breastration kits). Typical pH values for wines would be between 3.2 and 3.6, roughly. Wines with higher pH (lower acidity) are at increased risk of spoilage.
If you are just starting out, start with a breastration kit. Generally they come with instructions. You can also read Lum Eisenman's discussions of various types of tests (chapter 23) in The Home Winemaker's Manual, at
Happy fermenting --
Doug
