Do different powders (for example cocoa powder, wheat flour, health drink powder, baking powder) measure different numbers of grams per tablespoon? If yes, why and how do I find out how many grams per tablespoon a given powder is?
3Your profile says you're as software developer, so you can probably deal with these data files: ars.usda.gov/Services/docs.htm?docid=8964 ... that's probably your best single source of weight to volume conversions (and nutrition info, etc.)– derobertFeb 25, 2013 at 15:59
1I voted to close, because your examples indeed have a different density, and the list is endless. You can use online converters if you want to know something specific, or ask it on the site if you can't find it.– MienFeb 25, 2013 at 16:04
@Mien " or ask it on the site if you can't find it". What? The converter?– Aquarius_GirlFeb 25, 2013 at 16:20
Some ingredients are so specific or local, that you can't find them in the online converters.– MienFeb 25, 2013 at 16:50
1@Mien Send me a few cakes to check, I am sure you are just fine! :-)– TFDFeb 26, 2013 at 9:27
It varies by material. A tablespoon (or millilitre) is a unit of volume; a gram of weight. The ratio between the two is called the density, and that varies a lot.
So, you have to look it up, or weight it yourself. Or, if you're lucky, it's on the side of the package.
You can access some of the measurement conversions in the USDA NDB data files I posted a link to via the much-more-friendly web interface. Cocoa powder gives you weight per tablespoon, exactly what you want. Unbleached AP flour gives 125g/cup, and you can convert that to tbsp (since cup is also a measure of volume; Google will happily tell you there are 16 tbsp per cup. (In general, they try to give useful measurements. E.g., "small" and "large" for onions, "stick" for butter, etc.)
From just those two examples, you can see one is 5.4g/T and one is 7.8g/T, so you can't just use one number for all fine dry powders.
This question cannot be answered in general--each substance or powder has a different density.
For example, table salt is approximately 6 grams per teaspoon (18 grams per tablespoon); ground cumin is about 2.5 grams per teaspoon (7.5 grams per tablespoon).
Furthermore, for some powders, how tightly they are packed--this is especially important with flour--will make a large difference. Other powders, like health drink powder, are going to be proprietary to their manufacturer.
When you are interested in a particular ingredient conversion, googling something like "XXX grams to teaspoon" will usually find you answers very quickly.
1You forgot moisture content. Home baking is done with volume because shelf stored products increase in moisture over time. Commercial made products use weight since bulk fresh product has known and standardised moisture levels– TFDFeb 25, 2013 at 19:03
I didn't forget it, but I did leave it out, figuring it was not actionable in any case, even if we do measure by weight at home :-)– SAJ14SAJFeb 25, 2013 at 19:15
Found these websites useful for conversions of measurements: