Retail sales rose modestly in August, marking the 11th consecutive month of gains, according to the CNBC/NRF Retail Monitor, powered by Affinity Solutions, released today by the National Retail Federation.

"Retail sales climbed steadily once again in August," NRF President and CEO Matthew Shay said. "Supported by low unemployment and steady wage gains, households remained budget-conscious but took full advantage of back-to-school promotions to stretch their dollars. Retailers stayed committed to affordability, keeping everyday products accessible for American families."

Total retail sales, excluding automobile dealers and gasoline stations, were up 0.22% seasonally adjusted month over month and up 3.87% seasonally adjusted year over year in August, according to the Retail Monitor. Sales increased 0.32% month over month and 5.15% year over year in July.

The Retail Monitor calculation of core retail sales (excluding restaurants in addition to auto dealers and gas stations) was up 0.17% month over month in August and was up 3.47% year over year. Sales increased 0.3% month over month and 4.72% year over year in July.

As a result of the new Retail Monitor methodology, the month-over-month and year-over-year total and core retail sales figures this month are not directly comparable with the figures from July. The full release, with enhanced sector details and dollar levels, will launch in October.

Unlike survey-based numbers collected by the Census Bureau, the Retail Monitor uses actual, anonymized credit and debit card purchase data compiled by Affinity Solutions and does not need to be revised monthly or annually. Beginning with this release, the Retail Monitor uses a new methodology that weights the card data to reflect the makeup of U.S. consumers and projects it to match U.S. Census Bureau retail sales totals.

Year-over-year comparisons are now reported on a seasonally adjusted basis, consistent with the month-over-month figures. Month-over-month and year-over-year changes are calculated on the updated basis and are not directly comparable to previously published Retail Monitor figures.