Inventories rose to $1.668 trillion. Sales rose to $1.297 trillion.
The monthly figures adding up manufacturing and trade inventories were in line with the consensus forecast.
Inventories are up 3.1 percent from August 2012, while sales have risen 4.2 percent from August 2012.
The total business inventories-to-sales ratio was 1.29, based on seasonally adjusted data, the Census Bureau said. A year ago, the ratio was 1.3.
The ratio indicates how long it will take to sell existing inventory at current prices. As the ratio rises, it indicates manufacturers may have too much inventory on hand and may adjust by slowing production.