Optimism among U.S. small business owners unexpectedly strengthened and topped estimates in July, thanks to improved expectations for business conditions, real sales and expansion, survey results from the National Federation of Independent Business showed.

The small-business optimism index rose to 104.7 last month from 103.3 in June. The consensus estimate of economists polled by Econoday was for a reading of 103.0.

A net 22% of survey respondents expect higher real sales volumes, up five points from the previous poll.

Twenty-seven percent of owners said they were planning to make capital outlays, up 1 point from June's survey.

The net percent of owners expecting the economy to improve was up 4 points to 20%.

Job creation slowed as respondents said finding qualified workers remained their biggest challenge.

"Contrary to the narrative about impending economic doom, the small business sector remains exceptional. This month's index is a confirmation that small business owners remain very optimistic about the economy but are being hamstrung by not finding the workers they need," said NFIB Chief Economist William Dunkelberg.