What size am I?

Buy clothes online can be a maddening experience. Different shops and different fashion labels have varying definitions of "Size 6." Fitting information might be hidden away on a clothing retailer's website, but it's hardly ever easy to compare data across companies.

That's the problem Web developer Anna Powell-Smith wants to solve with the data visualization app What Size Am I?.

Women input their bust, waist and hip measurements then the site gives the probable best fits for a variety of American and British clothing shops. To learn more, DW spoke with Anna Powell-Smith.

Deutsche Welle: You have created this new web app, called What Size Am I? Can you summarize what it does?

Anna Powell-Smith: Basically it's for women who are buying clothes in the UK or in the US. What it lets you do is go to the site, and put in your measurements - your bust, waist and hips - in centimeters or in inches, and then it will show you what size you are at 15 or 20 different stores in the UK or in the US. The differences can be quite large. So you can be a size 10 in one store and a size 14 in another store and I think this is the first place that lets you see what sizes you are in all of those stores, in the same place.
One of the most interesting things about data visualization is that it lets you take a data set and understand it in a new one. So once you'd created this, what new insight did you gain into fashion design?

There were a few things. Basically every shop has one set size that they size to. They will have a size 10, and the size 12 will be exactly two inches larger on all three dimensions - bust, waist and hips - and the next size will be exactly two inches larger. I don't think women expand that evenly. They're not differentiating as people get larger. Secondly, sizes really are very different. I found a size 16 in one store that was 10 centimeters larger than a size 16 in another store, which is really quite a big difference. Thirdly, different stores size to different body shapes. Some are very hourglass-shaped, and some are more pear-shaped, for larger hips, and some are straight up and down, and so one of the things that is useful is that you can work out which store is better for your body type.

Have you had any reaction from fashion designers or clothing shops?

I've had people on Twitter who run boutiques say that it was useful. I have a friend who works for a startup called Metail, who got in touch and said it was very exciting. I haven't had any retailers get in touch with me, and I don't know why that is.

Now that you've compiled all of this data, does this confirm longstanding suspicions that you had about fashion designers?

It actually surprised me a bit. Because I had thought that clothes that were more expensive tended to have smaller sizes and that clothes that were more mass-market tended to be larger. But I found the opposite was true. Certainly in the UK, the mass market store, a size 10 is a smaller size than the more expensive stores, where it is larger. I think that maybe is because the pricier stores have older customers, so they want to flatter people, but it was the opposite of what I expected.
You got a huge amount of data - was it easy to get? Or did you go to stores and measure clothes?

I didn't do any measuring. It's all official data that is published online by the stores themselves, so what I did was go to every stores websites, collect it, and type it up into my spreadsheet. So it didn't exist online in one space before. But it is official data. If you want to buy a dress from a shop, they will tell you what their measurements are. I just collected it while watching television.

Was there a particular moment or incident that made you want to do this?

Well, I buy a lot of clothes online, and it annoyed me that I would buy something in two or three different sizes and I would send some back every time, because I didn't know what size to buy. Then I saw a New York Times article that was an infographic about size 10 in American stores, and the range that a size 10 could be, and it was an enormous range. But it was just a static infographic and at that moment, I thought I could make an interactive version where people can put in their own sizes and it will tell them what size they are and that it would be useful as well as interesting. That's what inspired me.

For now you only have measuring information for American and British retailers. Conceivably you could add retailers from other parts of the world. It's just a simple matter of inputting the data. Is that right?

Yes. If a store publishes their sizes online, there's no reason I couldn't add them for other countries too, if there's demand for that.

You have made this application specifically for women, do you have any plans to expand it to men?

Yes, some people have asked for that. If enough people write to me and say they would like that, then yes. Quite a few people have asked for children, because children's clothing is sized by age. So a two-year-old size is even vaguer than a size 10, because two-year-old can be a huge range of sizes. If I have time I might do a children's version.

Interview: Cyrus Farivar
Editor: Sean Sinico