The human body is a complex shape. Some of our bodies are, unfortunately, more complex than others.

American sizing standards make buying clothing even more vexing. The U.S. sizing system is based on data collected more than 60 years ago from young, white, hourglass-shaped women — and manufacturers often don't follow those standards anyway. Some even practice "vanity sizing," or labeling clothes a size smaller, so customers can feel better about what they're trying on.

So what happens when you take away the dressing room altogether?

Online shoppers spent $10.2 billion on clothes in 2004, an increase of 24 percent over 2003, but poor fit is the leading reason for returns. Retail Web sites provide detailed body-measurement charts, and one Web site, www.fitme.com, can translate body measurements — up to 25 separate dimensions — into optimal sizes for hundreds of retailers.

Customers who buy clothes over the Internet, only to discover they don't fit, are often too lazy to send them back, says John Mincarelli, professor of fashion merchandising at the Fashion Institute of Technology in New York. "They're going to stop buying. If it fits, they're going to keep buying."

So online retailers are finding new ways to ensure proper fit, which in turn increases customer satisfaction and brand loyalty — in a word, sales. Land's End, one of the earliest Internet retailers, has been leading the way with its virtual model, an interactive mannequin that can be programmed to assume a customer's shape, skin tone, hairstyle and facial features. Nearly a million models are created each year.

Land's End introduced the virtual model in 1998. It lets customers try on clothes, accessorize and mix and match outfits. (Or see how they'd look in those outfits if they were 20 pounds thinner.) Last year, it introduced "virtual fit," which, with a few more measurements, will recommend sizes for the company's most popular items of clothing.

"We are in a world where video games make more money than movies," says Louise Guay, the CEO and founder of My Virtual Model. "People love to play. You provide them with an experience, the shopping experience where it's simply fun. It's easy and it's about them."

Maybe too much so, says Ed Gribbin, the president of Horsham, Pa., technology firm Intellifit Corp., which is trying to market its body-scanning tool to retailers. "The vast majority that we've talked to don't want to see their body, don't want to see their image. It's more information than they need to know."

Like virtual models, body scanning has been around for a few years, but it has been used more for custom clothing than for size prediction. Most of the machines required customers to disrobe and don tight-fitting shorts and top, something the casual shopper might not be inclined to do.

Intellifit's body scanner uses low-power radio waves to quickly collect accurate body measurements while the shopper remains fully clothed. Participating retailers have provided the company with their garment specifications, and a computer translates the shopper's measurements into the most appropriate fit.

The company plans to install the scanners in shopping malls (one is already in place at Willow Grove Park Mall outside Philadelphia). Shoppers will be able to use the scanner to find the brands and sizes that fit them best at stores including The Gap, American Eagle Outfitters, Lane Bryant, J. Jill, and with Macy's and Bloomingdale's private-label clothes.

Eventually, shoppers will be able to create an account that will store their measurements and allow them to shop online.

Intellifit has temporarily installed a scanner at Catherine's in Edison, N.J., where the larger-size retailer is using the data to update its sizing and specifications.

Catherine's salespeople can translate the scanned measurements into proper sizes for customers. Shoppers must remove large metal objects like keys, cellphones or jewelry before stepping into the large, round, see-through booth. With their arms at their sides, they stand still for 10 seconds while the scanner arm whips around the perimeter.

"People love to go in here," says Catherine's manager Susan Mayes — after they get one question answered first: "It doesn't broadcast my size, does it?" (Not to the whole store, no.)