How many teaspoons equal 3.4mg?

You can't directly convert milligrams (mg) to teaspoons (tsp) because they measure different things:

* Milligrams (mg) measure weight or mass.

* Teaspoons (tsp) measure volume.

To convert between weight and volume, you need to know the density of the substance you're measuring.

For example:

* 3.4 mg of salt would occupy a different volume than 3.4 mg of water.

To get a meaningful conversion, you need to tell me what substance you're working with.