The federal government measures poverty in the United States using 2 different calculation methodologies. The US Census Bureau reports on poverty based on the Official Poverty Measure (OPM) and Supplemental Poverty Measure (SPM).
The OPM metric has been in place since 1963 and looks at pre-tax income against a threshold that is set at 3x the cost of a minimum food diet in 1963 (in today’s prices), adjusted for family size. This metric measures income, threshold, and family to estimate what percentage of the US population lives under the umbrella of poverty.
The SPM metric, first introduced in 2011 was and is currently used to provide a more well-rounded view of poverty in the United States. As its name suggests, it is used in conjunction with the OPM, not as a replacement measure. SPM was designed to take contextual social, economic, and governmental factors into account that impact household incomes and cost of living. Elements of data such as geography, housing costs, the composition of family members, and more are part of the overall calculation.
Take a look at the below table to see the differences between OPM and SPM metrics: