WASHINGTON — When the Census Bureau said in September that the number of poor Americans had soared by 10 million to rates rarely seen in four decades, commentators called the report “shocking” and “bleak.” Most poverty experts would add another description: “flawed.”

Concocted on the fly a half-century ago, the official poverty measure ignores ever more of what is happening to the poor person’s wallet — good and bad. It overlooks hundreds of billions of dollars the needy receive in food stamps and other benefits and the similarly formidable amounts they lose to taxes and medical care. It even fails to note that rents are higher in places like Manhattan than they are in Mississippi.

On Monday, that may start to change when the Census Bureau releases a long-promised alternate measure meant to do a better job of counting the resources the needy have and the bills they have to pay. Similar measures, quietly published in the past, suggest among other things that safety-net programs have played a large and mostly overlooked role in restraining hardship: as much as half of the reported rise in poverty since 2006 disappears.

The fuller measures have also shown less poverty among children but more among older Americans, who are plagued by high medical costs. They have shown less poverty among blacks but more among Asians; less poverty in rural areas and more in cities and suburbs, where the cost of living is high. And they have found fewer people in abject destitution, but a great many more crowding the hard-luck ranks of the near poor, who do not qualify for many benefit programs and lose income to taxes, child care and medical costs.