The University of Michigan's preliminary August consumer sentiment index reading was 73.6, compared to the final July 72.3, and the final June 73.2 reading, according to market sources.
The expectations index was 64.5, compared to 65.6 last month, and 67.8 in June.
The current conditions index was 87.6, compared to 83.2 last month, and 81.5 in June.
Economists polled by Thomson Reuters had predicted a 72.5 reading for the main index, 83.0 for current conditions and 66.5 for expectations.
The five-year inflation expectation index was 3.0%, compared to 2.7% in July and 2.8% in June, while the one-year inflation expectation index was 3.6%, compared to 3.0% in July and 3.1% in June.
The University of Michigan index is not released to the press, but only to paying subscribers.