Most measuring mistakes are small. You are out by a few grams of flour and the cake is slightly denser than it might have been. Salt is not like that. Get salt wrong and the dish is wrong, and there is no fixing it afterwards.

The same teaspoon, half the salt

Salt is sold in crystals of wildly different sizes, and a measuring spoon measures space, not salt. Bigger crystals mean more air between them and less salt in the spoon:

  • Fine table salt, about 6 g per teaspoon. Small, dense, uniform crystals that pack tightly.
  • Morton kosher salt, about 5 g per teaspoon. Flatter, rolled crystals.
  • Diamond Crystal kosher salt, about 3 g per teaspoon. Hollow pyramid crystals, mostly air.
  • Flaky sea salt, less again. Large thin flakes designed to sit on top of food, not dissolve into it.

A teaspoon of Diamond Crystal holds half the salt of a teaspoon of table salt. Two brands, both labelled kosher salt, differ from each other by nearly 40%.

Which direction the error runs

A recipe written for Diamond Crystal that asks for two teaspoons expects about 6 g of salt. Measure two teaspoons of table salt into it and you have added 12 g. That is not a seasoned dish, that is an inedible one.

The reverse is gentler but still wrong. A recipe written for table salt, made with Diamond Crystal measured by the spoon, comes out flat and under-seasoned, and most people reach for more salt at the table without ever working out why.

Brining and curing are where this gets expensive. Those recipes are built on salt concentration, and being out by a factor of two ruins the whole batch rather than one plate.

What to do about it

Weigh it. Grams are grams whatever the crystal looks like. If a recipe gives salt in grams, the brand stops mattering entirely.

Or find out what the recipe assumed. Most serious American cookbooks state their salt somewhere in the front matter. If it says Diamond Crystal and you have table salt, use half as much by volume. If it says table salt and you have Diamond Crystal, use twice.

Or pick one salt and stay with it. Cooking is largely calibration. Once you know what a pinch of your salt does, you can adjust anything by taste, as long as you do not swap the salt without noticing.

The salt conversion page has the full table, including sea salt and flaky salt, along with the per-teaspoon figures.