American business plans to spend $173.3 billion for new plants and equipment during 1972, 12.7 percent more than last year, the Commerce Department said yesterday.

The increase, based on a survey conducted in late April and May, is 1.4 percentage points larger than the department had estimated three months ago.

"(The figures) seem to indicate a little more bullish picture than we had three months ago," said John T. Woodward, a Commerce spokesman. "In view of what people are saying about a possible recession later this year, I think these figures are good news."

The figure is not adjusted for inflation. The department said that if price increases for capital goods are similar to last year's, the latest survey implies that real spending will increase about 4.5 percent in 1979, compared to 5 percent in 1978.

The upward revision of 1979 spending plans was primarily in non-manufacturing, the department said, including airlines, commercial firms, mining, electric utilities and communication firms.

In manufacturing, there were sizable upward revisions in paper, textiles, chemicals, petroleum, nonterrous metals and aircraft. There were downward revisions in iron and steel, nonelectrical machinery, and stoneclay-glass.

Capital spending in the first quarter of 1979 increased 1.2 percent to a seasonally adjusted annual rate of $165.9 billion, after a sharp 5.5 percent increase in the fourth quarter of 1978. Business plans 2.5 percent increases in the second and third quarters and a 3.5 percent increase in the forth, the department said.