While customers burn over the high cost of clothing this year, designers are fiddling with the length of hems.

This season's tune should please women with dwindling dollars to spend, since choice of hemline lengths has been passed on to the customer, who can wear the same style skirt above the knee or above the ankle.

Or somewhere in between.

As Karl Algerfeld says of this year's collection for Chloe: "One hem length is demode." Last year, Lagerfeld says, most of his customers asked that his ultra-short minis be extended to traditional knee length. Now he won't have to concede a thing.

Some styles are shown in both long and short versions. Others, including a group of charming school-girl dresses with white collars and cuffs in pleated blue flannel, are cut to the knee. And some of the knit skirts come closer to looking like knit shirts.

"I like the short sweaters, chemises and tights," noted Joan Karl of Garfinkels. "They would be perfect for a party in Georgetown in the evening."

Kenzo Takada of Jungle Jap, whose customers have never really given up their miniskirts, successfully showed tweeds and knits in both lengths.

"Customers would prefer to be directed, but at the same time don't want to be forced," says Ellin Saltzman of Saks Fifth Avenue. Saltzman points out that long coats in the winter make great sense, adding "And the long (near ankle length) fluid skirts at Chloe and Kenzo look devastating."

"After a customer bought an expensive coat last season, and paid to have it shortened, it will be hard to explain why she can wear it longer now," says Val Cook of Saks-Jandel.

What separates this crop from the mini-maxi period of the late '60s are broader shoulders and softer fabrics. What's more, the high boots that used to cover the gap between the foot and the hemline have been replaced by thick, ribbed tights worn with flat or low heeled shoes, and sometimes low boots.

If knee length is the safety zone for skirts, it's the big question mark for pants. Most designers, including Giorgio Armani, Sonia Rykiel, Valentino, Claude Montana and Lagerfeld, have shown knee pants for both daytime and evening.

"It's a wonderful solution to knobby knees," says Kay Kerr of Neiman-Marcus, who prefers Valentino's versions to anyone else's. "You can sit in them and look like a lady. You don't have to worry about the top of your pantyhose showing. And you can get in and out of small cars with ease," she says.

And isn't that what clothes are supposed to be all about?