Quantity based MBIs or ‘market creation’ instruments create a market in the rights to engage in an activity (that may be associated with environmental damage) by restricting the total level of activity and allocating the right to participate. An efficient allocation of rights is determined through a market mechanism.

Quantity based MBIs are used when it is important to get a certain environmental outcome - for example, when exploitation of an ecological community is close to a level that may cause irreversible or unacceptable degradation. For example greenhouse gas emissions are increasingly being traded in carbon markets and environmental offsets are increasingly being required for developments that clear native vegetation.