I’ve been dying to have a fashion designer in this spot for a very long time. So when designer Sole Salvo‘s message arrived in my inbox on Friday morning, I was thrilled! As an avid sewer — who doesn’t like using patterns — I am fascinated with the process of fashion design. I know there is a lot of math involved. Some of it has to be a gut instinct — how will this angle work on a human body? And some of it is very calculated — what do I need to add in order to get a 5/8″ seam allowance?

Sole has been working as a designer for nine years, currently working for a large clothing company in New York. Here’s how she uses math in her job.

Can you explain what you do for a living?

I design women’s clothing. I sketch new styles then give the specs (measurements of the garment, like length, waist measurement, neck drop etc) to the tech designer or pattern maker to make a sample. I pick out fabrics, colors and trims, like buttons and thread, to complete the look of each garment. Once my seasonal collection is complete, I review it with my merchant team who decided what to buy for the store.

When do you use basic math in your job?

Math is important for design. We have to measure our sample garments to know where we need to add or subtract fabric to make the garment fit well. Additionally a strong understanding of geometry is important for understanding how the flat pattern shape will make up into a 3D garment as well as what part of the flat pattern to change to fix the fit.

Do you use any technology (like calculators or computers) to help with this math?

I usually don’t use technology for this myself because the calculations I have to do are usually simple, like adding 1/4″ here and 1/8″ there, but my cross functional partners on the tech team do use a computer program to digitally manipulate the flat garment pattern. I use Illustrator to draw my flat sketches — these are the detailed sketches that the factory pairs with the measurement specs to make up the sample. These drawings have to be very accurate and clear so the factory can see each detail of stitching and seaming, as well as the overall proportion and look of the garment.

How do you think math helps you do your job better?

Without math it would be impossible to keep sizes consistent, and it would be impossible to draft a garment pattern. In addition it would be impossible to create trim pages — the list of trims required to make a garment. We use numbers on those as well to tell the factory how many buttons to use on each shirt. The factory must multiply the number of buttons by the number of shirts they are making to order enough buttons. It becomes very important when ordering because if you make a little mistake on a style that has 100,000 pieces on order, all of a sudden you could wind up with 100,000 too many buttons!

How comfortable with math do you feel?

I feel very comfortable with math in what I do. I deal with whole numbers and simple fractions for the most part.  I also have a strong sense of geometry. I can visualize what a pattern piece would look like if it is draped on the body, and this helps me design and also helps me make comments in my fittings.

What kind of math did you take in high school?

I took algebra, geometry and calculus.  Algebra was manageable, geometry I could do with my eyes closed. I can essentially reander 3D models in my head, so anything that involves shapes and how to manipulate them comes naturally to me. Calculus was more of a challenge. When it came to doing more complicated problems, I struggled. I did ok in the end, but I had to really study in calculus.

Did you have to learn new skills in order to do the math you use in your job?

Knowing how to add fractions comes in handy every day.  Also area is important. If you are working on a garment, sometimes the size might be right, but the fabric is just distributed in the wrong place. To fix it, you might have to keep your total area the same, but just shift it around to make it lay flat or to drape just the right way.

Thanks so much, Sole! If you have questions for her, ask them in the comments section.