WASHINGTON - US gasoline prices may be falling at a fast clip and easing the burden for cash-strapped households, but don’t expect a significant boost to economic growth this quarter.

Prices at the pump have dropped by about 29 cents per gallon or 8.2 percent since the end of September to an almost two-year low of $3.27, according to the latest government data.

But given that gasoline prices fall anyway during this time of year, the price decline is a less impressive 4.4 percent when adjusted for normal seasonal variations.

Economists estimate the drop in gasoline prices will add roughly $2.5 billion or a tenth of a percentage point to fourth-quarter consumer spending.

“It lends a little bit of some upside to the holiday shopping season,” said Ryan Sweet, a senior economist at Moody’s Analytics in West Chester Pennsylvania.

There are already some suggestions the drop in prices has freed up cash and given a lift to discretionary spending.

Sales at major retailers rebounded strongly in the week ending Nov. 6, according to a report this week from the International Council of Shopping Centers and Goldman Sachs.

The increase followed two straight weeks of declines.

“The ongoing decline in gasoline prices is providing a modest tailwind to consumption at a critical time of the year for retailers,” said Carl Riccadonna, a senior economist at Deutsche Bank Securities in New York. “The price weakness is essentially a form of economic stimulus.”

Ben Herzon, a senior economist at Macroeconomic Advisers in St. Louis, cautioned, however, that the benefit of lower gasoline prices would not be enough to “materially offset the drag that we will see from declining inventory investment and the government shutdown” in terms of economic growth.

A faster pace of inventory accumulation helped the economy to grow at a 2.8 percent annual pace in third quarter, but businesses are expected to draw down inventories this quarter.

At the same time, economists estimate the 16-day partial shutdown of the federal government in October will shave as much as 0.6 percentage point from fourth-quarter gross domestic product.

In the end, economists think GDP will advance at a rate of less than 2 percent in the final three months of the year, even with a little help from declining gasoline prices.

Apart from the normal low seasonal demand, gasoline prices are being pushed down by relatively soft crude prices that reflect a weak global economy and increased domestic production.

U.S. crude oil output surpassed imports in October for the first time since 1995. If the trends hold, prices at the pump could remain low even in the summer when they typically rise.

While the boost will be minimal this quarter, the low gasoline prices are helping to strengthen the fundamentals for consumer spending and preparing the economy for a strong take off next year once the fiscal headwinds fade.

Goldman Sachs expects the economy to grow between 3 percent and 3.5 percent next year.

“On top of higher household net worth, easier credit conditions, a smaller headwind from the 2013 tax hikes, and a likely modest improvement in wage growth, lower gasoline prices are one further reason to anticipate a pickup in consumer spending,” said Kris Dawsey, an economist at Goldman Sachs in New York.