With Fitday you can put a custom ingredient in at the value you use for it.

Doug Freyburger wrote:
|
| Different people calculate net carbs differently so the word "true"
| for a net carb count is a misnomer. I experimented on myself and
| concluded that my body absorbs sugar alcohol as carb grams so I count
| them fully. I also distrust net carb claims on some labels and I
| consider their claims carefully before accepting them. In the end I
| decided that the only deduction I'm willing to take is for fiber.
|
| This is part of the deal with fitday being a generalist tool not
| specific to low carb. I think you want one that is specific to low
| carb and one that has decided to calculate net carb grams based on
| your decisions about how to do that. I don't know of such a tool off
| the top of my head.