There isn't a direct conversion rate from grams to teaspoons for sugar because teaspoons measure volume and grams measure mass. The amount of sugar (in teaspoons) you get in a gram depends on the density of the sugar.
Here's a breakdown:

Density of Sugar: Granulated sugar has a density of about 0.59 grams per milliliter (g/mL) [1].

Conversion Process: If you know the density, you can convert grams to teaspoons using the following formula:
Teaspoons (tsp) = Grams (g) / Density (g/mL) / Teaspoon conversion factor (mL/tsp)
The teaspoon conversion factor depends on the specific definition of a teaspoon used. A standard US teaspoon is typically considered to be 5 milliliters (mL) [2].

Example Calculation: Let's say you want to know how many teaspoons are in 1 gram of sugar.
Teaspoons (tsp) = 1 gram / 0.59 g/mL / 5 mL/tsp
Teaspoons (tsp) ≈ 0.34 teaspoons (rounded to two decimal places)
Key Points:

This is an approximate value because sugar density can vary slightly depending on factors like granulation.

It's important to use the correct conversion factor for teaspoons based on the specific measurement definition being used.
Alternatives for Cooking:
In recipes, it's generally recommended to use measuring cups or spoons designated for specific ingredients like sugar to ensure accurate measurements by volume. This avoids the need for density conversions