@Justin Ramos and I have built a Size Calculator for our app, Peachi (https://www.peachi.io/), which will determine your clothing size across a plethora of brands. Right now we're focusing on menswear, but womenswear and even more brands are coming!
For background, Peachi is an AI powered clothing marketplace which is catered to you and your unique style. As you interact more with our recommendations, we understand more about your overall aesthetic for different occasions and tweak/better the outfits we present to you over time. Use our free Sizing Calculator to see how you size across different brands: http://bit.ly/peachi-sizematters
Feel free to message us directly with any feedback or questions and thanks for trying us out!