Four small mounds of salt on dark slate in different grain sizes, from fine table salt through coarse kosher to large flaky pyramids and damp gray sel gris, with a wooden spoon and a few scattered crystals

Does Salt Go Bad? Why It Keeps Forever, and What Clumps Mean

October 1, 2026

Salt does not go bad. It is a mineral, sodium chloride, and a box bought a decade ago is still salt. What does change, with time and weather, is the iodine added to it and the way its grains hold together. Grain also decides how much salt fits in a measuring spoon, which is why one teaspoon of kosher salt can hold about 70 percent more salt than another. The salting guide covers the cooking side, and the finishing salt guide covers the flaky salts in more depth.

Does salt expire?

No. Morton's own guidance is that salt itself has no expiration date; the date on the box reflects the iodine and additives, which can change over time. Iodized salt carries potassium iodide, and Morton notes that the iodine can dissipate over time, which is why it gives its iodized salt a five-year use-by window. (Morton gives its plain salts that contain an anticaking agent the same five-year window, because the agent can lose effectiveness and the salt may clump; its salts without anticaking agents get three years, for the same reason.) After five years an iodized salt is still good salt, though some of its iodine may have dissipated.

Why does salt clump, and how should it be stored?

Salt is hygroscopic. It pulls water out of the air, and sodium chloride begins to dissolve into a film of its own brine once the relative humidity around it passes roughly 75 percent. When the air dries again that brine recrystallizes and welds the grains together. That is the story behind a box that pours in October and comes out in one piece in August, and behind the shaker beside the stove that seizes while the one in the cupboard stays loose.

The fix is a lid. Morton's advice is to keep salt in a cool, dry place away from where the cooking happens, and in an airtight container when that isn't possible. Clumped salt has not spoiled, and Morton's advice is to tap or shake the package to break the clumps up. The pantry storage guide files salt with sugar: anywhere dry, in an airtight jar, keeping indefinitely.

Is sea salt healthier than table salt?

Table salt, kosher salt and most sea salts are sodium chloride, and all are about 40 percent sodium by weight, which is the chemistry of the molecule. The American Heart Association adds that table salt and most sea salts have the same basic nutritional value. What goes into the box differs. Morton's iodized table salt carries potassium iodide, dextrose and calcium silicate alongside the salt, while sea salt is evaporated from seawater, as the sea salt harvesting guide describes. Where sea salts differ is texture and use, such as the way a crystal sits on a finished plate.

What makes pink Himalayan salt pink?

Traces of iron oxide. A 2020 study in the journal Foods, which analyzed the mineral composition of pink salts sold in Australia, notes that the color comes from them. Jacobsen Salt Co. packs a Pink Himalayan Salt in a refill jar (shop Jacobsen Pink Himalayan Salt).

Who needs iodized salt?

Iodine is an essential part of the thyroid hormones, and the adult recommended intake is 150 micrograms a day. American salt makers began adding it to table salt voluntarily in 1924, in Michigan, part of the goiter belt around the Great Lakes where soil and water are iodine-poor. The National Institutes of Health puts iodized salt in the United States at about 45 micrograms of iodine per gram, so a quarter teaspoon supplies roughly half a day's requirement. Dairy, eggs, seafood and seaweed carry iodine too. The NIH notes that sea salt, kosher salt and other specialty salts are not usually iodized, so a kitchen that wants iodine from salt needs a box labeled iodized.

Can kosher salt swap for table salt by the spoon?

Not one for one. By weight, table salt and kosher salt carry about the same sodium. By volume they differ, because a hollow flake or a coarse grain packs more air into a teaspoon than a fine cube does. The two American kosher salts differ the most: they share a name, but a teaspoon of one weighs about 40 percent less than a teaspoon of the other. The kosher figures below come from the manufacturers' own nutrition labels, scaled to a teaspoon; the table salt figures are estimated from the FDA's statement that about 2,300 mg of sodium is about one teaspoon of table salt.

Salt	Weight per teaspoon	Sodium per teaspoon	Iodized	Anticaking agent
Table salt, fine	About 6 grams (estimated from the FDA's teaspoon figure)	About 2,300 mg (FDA)	Only if labeled iodized	Calcium silicate in Morton iodized
Morton kosher	About 4.8 grams	About 1,900 mg	No	Yellow prussiate of soda
Diamond Crystal kosher	About 2.8 grams	About 1,100 mg	No	None

Measured by the spoon, a recipe written for Diamond Crystal will be about 70 percent saltier with Morton kosher and about twice as salty with table salt. A scale is the only clean way around it. The next best is knowing which salt the recipe writer used and adjusting from the table. The first salt recipe guide puts the grain-size lesson to work.

How much salt is too much?

The FDA's Daily Value for sodium, the figure behind the sodium line on nutrition labels, is less than 2,300 milligrams a day, about one teaspoon of table salt. The FDA puts average American intake at about 3,400 milligrams, and notes that more than 70 percent of it comes from packaged and prepared foods. That leaves less than 30 percent for everything else, including the salt added at the stove and the table. Anyone told by a doctor to restrict sodium should follow that advice.

What do the label additives do?

On the label	What it is	Why it is there
Calcium silicate	A mineral powder the FDA lists as generally recognized as safe at up to 2 percent in table salt	An anticaking agent that keeps the grains from clumping
Yellow prussiate of soda (sodium ferrocyanide)	An anticaking agent the FDA permits in salt at up to 13 parts per million	Same job; listed on Morton kosher
Potassium iodide	The iodine source in iodized salt	Supplies iodine for the thyroid
Dextrose	A sugar	Stabilizes the potassium iodide; Morton lists it in its iodized salt

Does salt actually preserve food?

Yes. Salt preserves by drawing water out of food and by holding back the growth of unwanted bacteria while letting desirable ones grow. A cured anchovy and a jamón are both applications of that principle. Salt inhibits microbes rather than sterilizing food, and the preserving effect depends on the full measure of salt a recipe calls for, which is why the National Center for Home Food Preservation warns against cutting back the salt in sauerkraut and fermented pickles.

Black salt, potassium salt and a salt with one ingredient

Burlap & Barrel's Black Mineral Salt is fired in a kiln with harad seeds, amla and babul bark, and the producer describes its flavor as savory, tart and eggy (shop Burlap & Barrel Black Mineral Salt). "Potassium salt" is potassium chloride, which the FDA allows to be labeled by that alternate name.

Burlap & Barrel's Salina Crystal Salt comes from Syracuse, New York, and its label lists a single ingredient, salt (shop Salina Crystal Salt).