This is a difficult question to answer.
It depends on the density of the pigment because whilst samples are usually measured by volume (1/4tsp), full jars are measured by weight (most, but not all, are 7.5g). Since different textures of pigment have different densities, 7.5g of different pigments will fill different volumes. So, basically, depending on the texture of the pigment and how tightly packed or not it is, you'll get a different number of 1/4 tsp samples out of a full jar.
However, for the purposes of estimating, it is generally said that a frost pigment contains roughly 3 full tsp, so around 12 x 1/4tsp samples. That's only a rough estimate though and you're likely to get more from some pigments and less from others.