Per Capita Income is derived by dividing total personal income (in the US, an economic report by the BLS) by the total population.
Per Capital Income is usually used as a national wealth indicator, especially when measured in a commonly used currency, it has several weaknesses however:
1) Economic activity that does not result in monetary income (such as homemaking and some artistry) is not counted in per-capita income measurements, although the magnitude of this effect varies widely from country to country.
2) The distribution of income is not gauged accurately in per-capita income measurements. This means that outliers within the population (the extremely wealthier or indigent) can have a disproportionate effect on the overall outcome.
3) Varying exchange rates between countries means that a given amount of money will have different value in different places, thus Per Capita Income offers imperfect comparison’s country to country, and may be most relevant comparing different years within a single country, when controlled for inflation
More commonly used indicators include Purchasing Power Parity (PPP) and other GDP measurements.