The serving size of flax is 3T so I'd guess about the same because the numbers are similar. Personally, if I just have 1T in my smoothie I don't count it but if I have chia pudding than I do count it as a nut/seed serving. This is just my random assessment though, not based on anything factual
It's one place where calorie counting as back-up helps me.
Baby steps, getting back on track 2015. Moving the next 10 lbs by the end of the summer.
Maintaining 48 lb loss since 2008, working off regain to a sensible maintenance level. 67 lbs and counting!