Local shoppers drawn to the Internet by promises of free shipping for holiday gifts may find themselves wishing they headed for a shopping mall instead.

Many of the offers exclude Hawai'i. A little more than half of 50 sites reviewed by The Advertiser ban Hawai'i from no-cost delivery promotions, including retailers such as Staples Inc., the largest U.S. office supply chain, and Kodak's online store.

"I encounter it all the time," said Kalihi resident Marilyn Paguirigan, a frequent Web shopper who's noticed the state's exclusion while reading the fine print of offers for free shipping. "You have to be aware of it."

Free shipping is one of the most prevalent promotions on the Internet during the holiday season. Many shoppers like the convenience of online stores, but aren't willing to pay for shipping, since the same item may be just a few miles away at a local mall. Forrester Research, a Cambridge, Mass.-based technology researcher, projects U.S. consumers will boost online holiday spending 25 percent from last year to $18 billion.

Amazon.com, the largest Internet retailer, has free shipping year-round, including to Hawai'i, and has said it is one of its most powerful marketing tools. Others Web merchants dial up the offer around Thanksgiving.

"It is the No. 1 incentive online," said Helen Malani, spokeswoman for Shop zilla.com, a comparison shopping site formerly known as Bizrate.com. So much so that Santa Monica, Calif.-based Shopzilla features a listing of them on its site.

"It's a way to close the deal and that's why a lot of retailers offer them."

Other sites, such as Yahoo! Shopping, also keep a running tab of free-shipping promotions because of their popularity. Among the most well-known of the programs is the "Super-Saver Shipping" program at Seattle-based Amazon.com that features free delivery for certain orders of more than $25. The offer is good for Hawai'i residents, though some items may be restricted from it, company spokeswoman Jani Strand said in an e-mail.

Other sites that don't exclude Hawai'i in their holiday no-cost delivery promotions include Ritz Camera, outdoor apparel catalog L.L. Bean and upscale department store Nordstrom.

Retailers that drop Hawai'i from their complimentary delivery offers may do so because it's more expensive to ship here than most Mainland destinations if they use UPS. Offering free shipping to the Hawai'i would chew through their profit margins.

Cooking.com, a California-based Web merchant, doesn't extend its free shipping to Hawai'i, though it does give local customers a break on shipping costs because of the promotion. The company said it probably loses money on shipments to Hawai'i, especially if it is running a promotion at the time.

A check of UPS' Web site shows shipping a five-pound box from San Francisco to Albany, N.Y., a distance of 2,600 miles, would cost $11.39 using the company's "ground" shipping rates. The same box coming to Hawai'i would be more than twice that at $24.71.

The five-pound package would most likely go to Albany via a combination of rail and trucks, while the package would be flown the 2,400 miles to Hawai'i. UPS, the world's largest package delivery company, is used by most Internet retailers that are attracted by its on-time delivery guarantees, reliability and other services. Some companies can contract with UPS to get cheaper rates than those in the example above, and rates are based on more than just mileage.

"There's definitely exorbitant costs when coming to Hawai'i," said Paguirigan, the Internet shopper from Kalihi. She once asked a Mainland vendor to make an exception and ship her purchase with the U.S. Postal Service's less expensive service, but she was turned down. "Sometimes when you factor in the shipping costs, it no longer makes sense."

Late last year the Postal Service introduced two priority-service boxes that can hold up to 70 pounds and be shipped from anywhere in the U.S. for $7.70.

Aaron Oya, a Postal Service small-business specialist, said he fielded a call from a frustrated Web shopper complaining about an online retailer's shipping rates to Hawai'i. "Someone called me and asked, 'Why don't you guys tell these companies to ship through you? I know you guys are cheaper.' "

In any event, free-shipping promotions could wane in coming years as Web shopping gains acceptance. Gone are the days of the dot-com bubble when Internet start-ups often lost money on orders to attract customers. Shopzilla's Malani said today's free-shipping offers often require shoppers to buy a certain amount.

A Shopzilla survey found that 35 percent of Web shoppers got free shipping during the Thanksgiving holiday week when many sites are likely to offer the promotion. That's down from 41 percent a year earlier.

"It's a way to close the deal and that's why a lot of retailers offer them," Malani said. But "giving away free shipping is expensive."

Reach Greg Wiles at gwiles@honoluluadvertiser.com.