The extra utility derived from the consumption of one more unit of a good, the consumption of all other goods remaining unchanged.
The hypothesis of diminishing marginal utility
This states that as the quantity of a good consumed by an individual increases, the marginal utility of the good will eventually decrease.
Units of Total Utility/ Marginal Utility/
X consumed mm TU (utils) MU (utils)
0 0 0
1 15 15
2 25 10
3 33 8
4 38 5
5 40 2
6 40 0
7 39 -1
Consuming 1 unit of X gives 15 utils of satisfaction, consuming 2 units gives 25 utils, and so on. The figure of marginal utility decline as each successive unit is consumed. If the consumer goes on consuming more and more units, eventually he reaches a point (the sixth unit) where additional units yields no extra satisfaction at all.