How many carbs are in a packet of splenda?

10 - 20 calories per packet There are 3.87 kcal per gram of sugar, so the answer depends on the size of the sugar packet, which is apparently not standard. Packets tend to vary from 2-6 grams. According to the USDA website, they list 2.8g packet = 11 kcal

Which would yield 16 kcal/ 4.2g teaspoon, and ~23 kcal/6g packet. Examples:

"Sugar in the raw" brand has 5g = ~19 kcal Domino brand packets have 4g = ~15 kcal