The U.S. consumer price index rose 3.4% in August from a year earlier, the same as July's increase and inside a range of historical forecasts for the indicator.

CPI is considered a key inflation data point that the Federal Reserve uses for interest-rate decisions based on its dual mandate of price stability and maximum employment.

For select economic indicators, including the CPI report, Dow Jones Newswires measures whether a reported statistic falls outside a historical range of Wall Street Journal forecasting, and if so, by how much. Those forecast ranges are based on an archive of surveys of economists the Journal has conducted over the past decade.

In the case of August's CPI, the range of Journal forecasts relative to the actual reported number over that period was plus or minus 0.1 percentage point. The indicator was in line with a Wall Street Journal forecast of 3.4%.

The ranges are made up of the median of forecasts over 10 years that came in lower than the reported number and the median of forecasts that came in higher.

Write to Jessica Coacci jessica.coacci@wsj.com