From shoes to jeans to little black dresses, there’s no substitute for trying on clothes before you buy them. But if you want to skip cramped dressing rooms and crowds and shop online, many online retailers have developed new tools that help you pick the right size.

Consumer Reports’ favourite tool is True Fit. It’s easy to use. You don’t have to do any measuring. You just answer a couple of questions, and it recommends a size for you. It also gives you fit tips about how the garment will fit your body. True Fit is available on 15 retailers’ sites, including Nordstrom and Lord & Taylor.

Consumer Reports also looked at Dressipi, another useful tool that works on Apple devices. You plug in the size you wear in your favorite brand, and the app will tell you the best size to buy for more than 500 other brands.

As for shoes? The tool Shoefitr helps you compare sizes among hundreds of brands and styles. Consumer Reports likes that it does a scan of the shoe and provides an accurate, 3D replica of the shoe. If you wear a size 8 in one particular brand of shoe,it can tell you that maybe you need a 7½ in another brand of shoe.

When it comes to jeans, Levi’s’ website offers a quiz so that you can ID your curve and find the best fit.

There’s also a space-age tool available in a few Bloomingdale’s stores. A scanner, like those used in airport security, takes precise measurements of your body, then gives you the right sizes and best fits for dozens of brands. It’s like an instant custom fitting and personal buyer all in one.