Table salt

One US cup of table salt weighs 292 grams. Going the other way, 100 grams is about 0.34 cups.

Table salt is the calibration point for salt entries on this site. It is the fine, iodized sodium chloride sold in cylindrical shakers everywhere, and its behaviour in a measuring spoon or cup is closer to granulated sugar than to a milled powder — hard crystals that pack tightly and consistently regardless of how the cup is filled.

USDA FoodData Central publishes 1 teaspoon = 6.0 grams, 1 tablespoon = 18.0 grams, 1 cup = 292 grams (FDC 173468, Salt, table). This gives a bulk density of 1.2342 grams per millilitre. King Arthur's ingredient weight chart publishes 1 tablespoon = 18 grams, which extrapolates to 288 grams per cup and 1.2174 grams per millilitre. The two figures agree within 1.4 percent, well inside the 5 percent tolerance we apply to the sugar category.

We publish the USDA figure because it comes with the underlying teaspoon and tablespoon numbers rather than an extrapolation from one, and because the source is a laboratory measurement rather than a chart entry.

Table salt should not be substituted one-for-one for kosher salt or coarse sea salt by volume. King Arthur publishes 1 tablespoon of Diamond Crystal kosher salt at 8 grams and 1 tablespoon of Morton's kosher salt at 16 grams — nominally the same ingredient at half the weight of one another. Compared to table salt at 18 grams per tablespoon, Diamond Crystal is roughly 45 percent by weight and Morton is roughly 90 percent. A recipe developed for one salt and executed with another using the same volume can be twice as salty or half as salty as intended, without any change in visible technique. That is not a rounding difference; it is a physics difference caused by crystal size and shape. Diamond Crystal's flakes are thin and irregular and pack loosely; Morton's are compressed cubes that pack more like table salt does.

The safest habit for a recipe that specifies salt without naming a brand is to weigh, or to ask which the recipe writer used. The next-safest is to use table salt with the caveat that half a teaspoon of table salt is roughly one teaspoon of Diamond Crystal kosher.

Sodium chloride's crystalline density is 2.165 grams per millilitre. The bulk density we measure in a spoon is lower because packed crystals leave air gaps between them; how much lower depends on crystal size and shape and how the spoon was filled. Table salt's fine, uniform crystals produce the highest bulk density of the common salts, which is why the same volume weighs the most.

Neither the FDA identity standard for iodized salt (21 CFR 100.155) nor the Codex standard for food-grade salt (CXS 150-1985) publishes a bulk density. Both focus on purity, iodine content and labelling. This is why manufacturer nutrition labels are the more useful cross-check for a specific brand.

The category here is 'sugar' rather than 'milled' because table salt's measurement behaviour matches granulated sugar and other free-flowing crystalline solids: it packs consistently and does not bridge or clump under normal use. The 5 percent category tolerance applies, and both sources sit well inside it.