Is this a fluoride free powder ?

Ingredients: calcium carbonate, pink salt, essential oils of peppermint, clove, eucalyptus, wintergreen, oregano and myrrh

Is there xylitol or stevia in this tooth powder?

NO xylitol or stevia. Ingredients are: calcium carbonate, Himilayin pink salt, essential oils of peppermint, clove, eucalyptus, globulus, wintergreen, oregano, and myrrh.

How many brushes do you get from one jar? Or rather, how long does 1 jar typically last?

Our first jar (3 oz) lasted the 4 of us about a month (a bit more) with brushing twice a day. I then purchased the larger size… we are 2 months in and about a quarter down. I guess it all depends on how much product each user uses per brush.