ABC News' Becky Worley reports:

Online shopping has one huge problem: you can't try on clothing and shoes over the Internet. The return rate for clothing purchased on the web is estimated to be anywhere from 25 percent to 40 percent. And with the rise of vanity sizing, it's almost impossible for a purchaser of pants to feel confident guesstimating size across different brands and styles.

New technologies are trying to change that: Levi's is asking shoppers to identify their body shape, bra company True & Co. asks women a veritable Cosmo Quiz about their lingerie to predict sizing, and a company called Truefit wants to create an online profile of your body shape based on the clothes you already own and love.

Truefit is the most ubiquitous of these new tools and it can be found on hundreds of different websites including some heavy hitters of apparel like Nordstrom and Macy's. Truefit is an algorithmic predictor of what size a shopper will be in a particular brand. To use one technology to explain another, it's like Pandora for the shape of your butt. If you like Justin Timberlake you might like Jason Derulo. If you are a size 28 in Citizens jeans, you'll probably be a size 6 in Lucky jeans.

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Looking for boyfriend jeans at Nordstrom.com, I see the Truefit icon and click. I need to create a profile and it asks for more than my email address and zip code. I give Truefit the brand and size of my two favorite pairs of jeans: a size 28 in 7 For All Mankind jeans and a size 4 in a pair of Anne Taylor skinny jeans. With those two data points, Truefit recommends that I get a size 28 in the two pairs of jeans I'm considering on the Nordstrom site.

Next I move on to shoes. I want to get a cute pair of metallic Sperry flats. I enter data into Truefit about the two pairs of shoes that fit me best: my size 9 Adidas running shoes and my beloved size 9 Cole Haan flats. Now I'll admit this is a bit of a test of the TrueFit technology because I already have a pair of Sperry Topsiders and they are a size 8.5. I would have ordered an 8.5 in the metallic flats without Truefit assuming the sizing is uniform across the Sperry brand. But True fit says to order a 9.

Once all the parcels arrive I start the trying on. To my surprise, the Sperry shoes fit perfectly. They are a little narrower than the other pair of Sperry's I had and the 8.5 would have been much too tight. Score that as a big win for TrueFit. The pants however are a different story: both the pairs have a 4-6 inch gap at the waist and droop considerably through the seat. They are both going to be returned.

I reach out to the CEO of TrueFit, Romney Evans. He says: "The service is constantly learning your size preferences from what you buy and what you return."

Fit is subjective, he points out, and with "multiple data points Truefit gets better and better. Just like Pandora, it takes a series of 'thumbs down' clicks for the service to get it right," he says.

Romney adds that the cumulative effect for online retailers is that they see their return rate decline significantly as the service gains traction: That is good for the retailer's bottom-line and the fit on the shopper's bottom. I for one will keep using Truefit. The idea of its progressive improvement makes sense and I'd like any help I can get with my online purchases.

Next I head to the Levi's site and try to identify myself based on their "Curve ID" parameters. I narrow it down to the two boxiest shape profiles: I'm going to be positive here and describe my figure as athletic and steer away from my more critical self who looks in the mirror and sometimes sees a rectangular bag of potatoes. So knowing that I am not one of their "Supreme Curve" options, they ask "Do you have straight hips with a bit of a curve?" or "some definition from waist to hip?" Some photos are offered, but in the end I guess on this and am assigned the designation of "Demi Curve."

I order my pair of Levi's accordingly and wait with much trepidation for their arrival. To my complete amazement, when the jeans arrive they fit like a glove. Honestly, I've never had a pair of Levi's that fit this well. I will definitely keep using their Curve ID service.

Finally, I try the True & Co predictive bra fitter. After a series of questions about the bras I already own, their tool asks me some questions about the shape and uhhh … behavior of my girls. It's actually very elucidating in its own right to consider why my existing bras fit the way they do.

The company also has an interesting business model to help with fit issues. Once you go through their questionnaire, they suggest about 30 bras. You input your credit card info, then pick up to six bras and they will send them to you without charging your card. Once the bras arrive, try them on, send back the ones that don't fit, and they will only charge you then for the ones you keep. Of the five bras they sent, four fit me well. Overall that's a much better ratio than the bras I select for myself as I walk through a lingerie store.

Finally a note about what was hailed as the future of online shopping fit technology: Back in the late 1990s and early 2000s, 3D body scanners were touted as the solution to this problem. Shoppers would get a full body scan in a device not unlike what you go through in the airport these days. You'd keep your data as a profile to be shared with online retailers for custom garments and virtual try-ons. Companies like Meality and Body Metrics set up shop in malls and department stores across the country. But the future of this technology is not resonating with consumers.

Getting scanned seems more like a TSA event or, worse, the result of some bad medical news. It's not pleasurable for us to imagine a wire-frame depiction of our body's "trouble spots" and it's unclear to the consumer what benefit really arises in everyday shopping experiences online: I've never had an apparel retailer ask me to upload my 3D body scan for a better fit.

So while the new online technologies for better fit like Truefit and Curve ID may not be perfect out-of-the-box, I for one will be using them as I try to avoid the mall and get the right size remotely.