There's confusion from the Justice Minister about how many joints can be made from the amount of cannabis legislated for in his draft bill

Andrew Little says those over 20 will be able to buy up to 14 grams of cannabis per day.

The matter will be subject to a referendum at next year's election.

But Little says he's seen various estimates about how many joints 14 grams would equate to.

He says they start at 42, go down to 21 or 15.

Little says he's not a user, so he's going off advice from his officials.