I wouldn't like to put an actual figure on it, a lot would say that I wasn't a low carber, but if you take the adverage daily intake that quite often banded around of 300g of carbs, then I differently a low carber, as I only really consume around 100-150g of carbs per day, give or take 10-20g's...
I think what is important though more than given a actually figure.. Is to first concider if one requires weight lose as part of the goal, as this will have some reflection to what you decided..
But the main goal, is to work out how the different types of carbs effect your blood glucose levels, cosidering both carbs types as well as portion size as your main guides.. Once you found these levels then you can decided if you need to loose weight, is this new level giving you good control, and is it achieving weight lose...
Sometimes just a selection of changes to ones diet, works very well can just be cutting down rather than cutting out certain foods might to wonders for control and weight lose..
But I think what is always a good tip though when losing weight, the slower it comes off, the more likely it is to stay off, and this also helps the body or should I say skin, shrink back to a better fit than it otherwise might do if large amounts are lost too quickly..