No matter how it is measured, inflation is at historically high levels. But the number that matters the most for low-income family budgets is grocery inflation, which runs at 13.2%.

After receding for several years, inflation, the precipitous rising of the price of goods and services, is back, and it's hurting the lives of U.S. consumers and businesses in several ways.

First, it's devastating family budgets of middle and low-income Americans and undermining the value of money set aside in conservative savings accounts that do not grow in value in line with rising prices.

Second, it pushes interest rates and the dollar higher, undermining America's export growth and the profitability of the nation's large businesses that draw a big chunk of their earnings from overseas markets.

Third, it threatens to push the nation's economy into another recession or another stagflation.

Fourth, it spoils the nation's mood, as evidenced in survey after survey. For instance, 18% of recent Gallup survey respondents named the old villain the top problem the U.S. faces, the highest since the mid-1980s.

But how high is inflation?

How does it affect the economy, especially the middle and low-income Americans who live under tight family budgets?

It depends on how it's measured.

First, there's the Consumer Price Index (CPI), a measure of inflation at the retail level, a proxy for the rise of the cost of living for consumers. It ran at an annual rate of 8.3% in April, near a 41-year high.

Then there's the Producer Price Index (PPI), a measure of inflation at the wholesale level, a proxy for the broad impact of inflation across the economy, including the competitiveness of the nation's businesses in global markets. It ran at 8.8% in April, also close to a 41-year high.

And there's Personal Consumption Inflation (PCE), another measure of the cost of living. It ran at an annual rate of 6.3% in April, very close to the 6.6% March record.

Grocery inflation (GI), compiled by Numerator's Inflation Insights Hub, provides weekly tracking of prices and consumer sentiment to find out how inflation impacts all shoppers. It was running at an annual rate of 13.2% in May -- well above the other three inflation numbers, with health and beauty prices running at an annual rate of 10.1% and household inflation rising at 15.8%.

That's terrible news for middle and low-income Americans who spend a more significant part of their family budgets on groceries proportionally.

"With inflation on the rise, consumers continue to pay more for their everyday goods. This is especially true for grocery products. And with grocery prices rising fastest in channels like Online, Dollar, and Mass, middle-income shoppers are disproportionately more impacted, as they typically spend more of their grocery dollars in these channels than the average consumer," Shawn Paustian, of Numerator Analytics at Numerator, told International Business Times.