It depends on the teaspoon size.
The following link shows a conversion table from Cubic centimeters to US Teaspoon:
http://www.aqua-calc.com/convert/volume/Cubic-centimeter-to-US-teaspoonHere's the conversion formulas:
from Cubic centimeter to US teaspoon: us tsp = cm³×0.2028841353
from US teaspoon to Cubic centimeter: cm³ = us tsp×4.9289216146