It makes sense that more people would buy clothes online if they knew the goods would fit. But it’s always a little bit of a guessing game: Would those jeans fit like a Size 10 or more like a Size 12? And only 10 percent of the $275 billion of apparel and accessories were purchased online last year, according to Forrester Research.

Now Macy’s has partnered with an intriguing start-up to make clothes shopping easier online. The start-up, True Fit, asks customers to complete a there-step profile where they pick brands and sizes that fit best. They also answers questions about their shape (Flat tummy? Average? Round?), height, and weight.  When they fill this out, Macy’s Women’s Denim Finder app will present a five-point scale: A 5 is very suitable to your figure — A 1 won’t fit at all.

“We’re thrilled to partner with Macy’s – a venerable retailer and innovation leader, who is on the cutting edge defining the very best experience for the multi-channel shopper. We’re excited to deliver this highly personalized service to their esteemed customers, and make it easier for them to find the right clothes and shoes at Macy’s,” said William R. Adler, True Fit’s CEO.

Before this, the industry standard was to offer a sizing chart online. “We don’t ask you to measure yourself,” Adler says. “We don’t care what you think your measures are or what size you think you are. That’s a measurement that’s fraught with error.”