250 milligrammes is equal to 0.0525 teaspoons of dry cooking ingredients like salt, sugar, and spice. A gramme, which is equal to 1,000 milligrammes, is about the same as 0.21 teaspoons. A quarter of 1,000 milligrammes is 250 milligrammes, so dividing 0.21 by four gives you 0.0525.
This is a change from mass to volume. These kinds of conversions aren’t very accurate, but for everyday things like cooking, the differences are usually small enough to be ignored. At the same volume, different ingredients have different mass values, so a teaspoon of one ingredient can be heavier than a teaspoon of another.
For an accurate conversion, a chef needs a large database of ingredients, preferably at different temperatures. This is necessary because when the temperature goes up, many materials get bigger, but their mass stays the same. This makes conversions less accurate.
