Here's some information from the Canadian website. Keep in mind that carbohydrates under 1 gram per serving have to be declared in Canada while in the USA carbohydrates under 1 gram per serving can be declared as zero.

SPLENDA*Granular contains maltodextrine and sucralose. Please see the nutritional information below:
Nutrition Information (Serving size 1tsp (5mL/0.5g)

Energy ...................2 calories(8 kj)
Protein.................................0 g
Fat......................................0 g
Carbohydrate.....................0.5 g
Sucralose............................6 mg

SPLENDA* Packets contain dextrose, maltodextrine and sucralose. Please see the nutritional information below:
Nutrition Information (Serving size 1g packet)

Energy................. 4 calories(17 kj)
Protein................................0 g
Fat.....................................0 g
Carbohydrate...................... 1 g
Sucralose..........................12 mg

The packets are the equivalent to 2 tsp. sugar which is why you need more bulk Splenda to sweeten.

Karen