Nancy Jones, vice president for marketing at Garfield & Marks, said customer feedback on the Fitlogic system was positive but that "we have not figured out how to get this concept out to our stores in a fashion they can accept financially and commit to in terms of space." There is little doubt that consumers would benefit from Fitlogic, or any other standardized sizing system, if it were widely adopted. Size, by definition a standardized measure, has become one of the most flexible concepts in retailing.

The creation of vanity sizes -- intentionally smaller than an objective size, to flatter the buyer -- has introduced pure guesswork into shopping. A size 10 from one clothing manufacturer is a size 8 from another and a 12 from still another.

According to a survey of 84,000 women, conducted by the NPD Group, a market research firm, 36 percent return a product every year because it does not fit. Those returns equal 12 percent of all clothing sales.

As a result, industry executives say, women shop at fewer stores and buy fewer clothes than they would if sizing were more transparent.

Julia Pierson, 46, from Baltimore, buys pants from one company, Jones New York, because it is the only brand that produces a size 12 that fits her. "My waist is disproportionately large," said Ms. Pierson, who was shopping in the Jones New York department at Macy's Herald Square, wearing a pair of Jones New York corduroy pants.

Fitlogic is the not the first company to tackle the sizing riddle. In the mid-1990's Levi Strauss developed a system that allowed consumers to order jeans cut precisely to their measurements. Using a different approach, a company called Intellefit designed scanning machines that took shoppers' measurements -- including shoulder slope and calf thickness -- in stores. And Neiman Marcus provides a kind of CliffsNotes to sizes in its catalogs.

But an industrywide solution has never materialized.

The developer of Fitlogic is Cricket Lee, who has frequently expressed her own frustration with clothing sizes. On Q.V.C.'s Web site, Ms. Lee describes herself as a 52-year-old who weighs 245 pounds, adding, "Like many women, I was unable to find clothing that fit and I was sick and tired of it." Ms. Lee declined to comment for this article.