Thanksgiving is next week, which offers some time before you buy gifts to get tips from the post office on mailing them early and cheaper.

The Postal Service expects to deliver 19 billion pieces of mail between Thanksgiving and Christmas this year. The busiest mailing day is expected to be Monday, Dec. 15 — with nationwide volume that day approaching 1 billion pieces.

About 8 million pieces of mail are expected to be processed at the Honolulu Processing & Distribution Center on that day, a 29 percent increase over the typical nonholiday mail volume. The busiest delivery day in Hawai'i is projected to be Monday, Dec. 22.

Duke Gonzales, a Postal Service spokesman in Hawai'i, said many local customers have already figured out the best tip for economical mailing: flat-rate boxes, which come at two prices and in three shapes.

"It's utilized more here than anywhere else in the nation," Gonzales said. The Honolulu district processed 792,889 flat-rate boxes in fiscal 2008, far ahead of second-ranked Seattle, with 612,780 boxes. San Diego was third with 607,548 boxes.

Flat-rate boxes allow you to pay one price no matter what you stuff in them, up to 70 pounds. The smaller box comes in two different shapes and costs $9.80. The price drops to $9.30 online, which includes free delivery confirmation, an added 65-cent value.

The larger box costs $12.95 if you buy it at the post office, but drops to $12.50 if you order it online. The weight limit for that box also is 70 pounds.

Honolulu postal service retail manager Nancy Wong has some ideas for using flat-rate boxes. She's looking at fitting six-packs of guava juice or passion-orange into an aloha-print cooler, nestled amid other goodies, including jams and other treats she used to think of of as too heavy to mail.

"I sent it last year and they loved it," she said.

Since last year, the post office Web site — www.usps.com — has made it much easier to figure out how to ship online.

The whole sign-up process now takes about five minutes, with the most time-consuming part being typing in the personal information, a user name and password.

Wong said the online domestic discounts are 3.5 percent to 5 percent for people who use click and ship, pay electronically and print out their own postage. She said international postage is discounted by 5 percent online, while rates for international express are discounted by 8 percent.

She said 40 percent of the priority mail handled by the Honolulu District post office is in flat-rate boxes. "They are so cost-effective."

Local candy company Menehune Mac has taken that extra step to adapt to the flat-rate boxes. Owner Susan Morita said the company has redesigned its boxes and gift baskets to fit into the flat-rate boxes.

The Kalihi-based candy company was founded in 1939 and has been run by her family since 1972. The company adapts its products to meet the market. For example, a current top seller is sugar-free dark chocolate macadamia nut candy, Morita said.

Morita said they had noticed that people would mail mostly candies, cookies and taro chips to keep the packages light. Now, with the flat-rate boxes, people will pack a bigger variety of heavier locally made items.

"The public just loves it," Morita said. "And it's good for us as well. They actually tend to buy more — local style, they're not going to send an empty box."

Morita said they've all improved their skills at clever packing, squeezing in the ahi jerky or filling the smallest puka with tiny jars of jam. Her staff is spared time and hassle with the flat price. "We don't have to put it on the scale and go to the post office."

She said the company has three locations at this time of year, the main factory on Waiakamilo Road, and two holiday stores, at Kahala Mall and Windward Mall.

Morita said the boxes are popular with people shipping gifts to folks in the military and even tourists shipping purchases back to Canada and Japan:

"We get a lot of Japanese tourists. They're very limited to how much they can take back with them." But Morita can tell them that eight boxes of macadamia nuts can can fit in a large flat-rate box.

The Postal Service is once again selling various holiday stamps, including ones with colorful nutcracker designs.

Those stamps can be purchased online as well as at retail stores such as Costco.

Those stores also still sell the Liberty Bell Forever stamps, which are a deal in price and convenience because the postal service sells them at the current postal rate but guarantees they are good forever — so you won't have to buy 1 cent stamps to cover future rate increases.

"Since Forever stamps went on sale in April 2007, the Honolulu District has sold over 50 million Forever stamps," Wong said.

In other postal news, Gonzales said there will be extended holiday hours at some post offices but not as many as previously, because the volume of mail has declined. Nationally, since September, he said, 9.5 billion fewer pieces were mailed than during the previous year, or 202.7 billion — a 4.5 percent decline.

Reach Robbie Dingeman at rdingeman@honoluluadvertiser.com or 535-2429.