Circle Skirt Calculator

Created by Bogna Szyk
Reviewed by Steven Wooding
Last updated: Dec 26, 2022

If your hobby is sewing and you're wondering how to make a circle skirt, our circle skirt calculator might be right up your alley! It will help you calculate the amount of fabric you'll need to create a perfect dress. We created this tool for one single purpose: to let you enjoy the sewing process without worrying about measurements. This calculator takes over all of the circle skirt math, making the preparations a breeze!

However, if you still want to learn all about circles and come up with your own set of formulas, do check out our circle calculator.

How to make a circle skirt

A circle skirt is a flowing skirt that, when spread out flat, creates the shape of a circle. It's very easy to sew; once the pattern is cut out of the fabric, all you need to do is sew two ends together, add the waistband and the hem... And yes, you're done! 😀

If you would rather prefer a pleated skirt, our pleated skirt calculator is here to help.

Circle skirt math

The most tricky part that makes many people avoid circle skirts is converting your measurements into an actual pattern. You will need two measurements:

  1. Your waist circumference, measured at the level of the waistband, and
  2. The length of the skirt, measured from the waistband.

Once you know these measurements, decide on the type of skirt. A full-circle skirt is made, as you could expect, out of a circular piece of fabric and will give you a full, voluminous look. 3/4 circle, half circle, and quarter circle skirts require less material and are more minimalistic in appearance. Don't believe us, calculate the area of a semicircle and compare it with that of a circle!

Once you know the type of skirt, calculate the radius from the center to the waistband:

  • R = waist / 2π - 2 for a full circle skirt;
  • R = 4/3 × waist / 2π - 2 for a 3/4 circle skirt;
  • R = 2 × waist / 2π - 2 for a half circle skirt; and
  • R = 4 × waist / 2π - 2 for a quarter circle skirt.

The - 2 at the end of each formula stands for the measurement diminished by 2 cm (seam allowance).

Then, calculate the fabric length you need according to this formula:

fabric length = length + R + 2

Again, the + 2 stands for the hem allowance.

After finding both the radius and the fabric length, spread out your fabric. You need to draw two circles with a common center: one of radius R and one of fabric length F. Follow the image below to cut out your pattern - and now, you can get straight to the sewing part of the process.

A clothing pattern to make a circle skirt
Credit: Béria L. Rodríguez @ Wikimedia Commons

Circle skirt calculator example

Let's try to plan a skirt together. Remember that instead of performing calculations by hand, you can always use the circle skirt calculator to help you with the math!

  1. Decide on the type of skirt. Let's choose a 3/4 circle skirt – not overly flowing.

  2. Take your waist measurement. Let's say it's equal to 75 cm.

  3. Decide on the length of the skirt. Let's assume it will be a midi skirt of length 60 cm.

  4. Use the formula for the waist radius:

    R = 4/3 × 75 / 2π - 2 = 13.9 cm

  5. Use the formula for fabric length:

    fabric length = 60 + 13.9 + 2 = 75.9 cm

Now, draw two circles with a common center, one with a radius equal to 13.9 cm and the other with a radius of 75.9 cm. That's it – you're done with the circle skirt math!


How do I calculate the waist radius for a circle skirt with a waist of 30.7 inches?

The waist radius equals 4.09 in.
To count the waist radius for a full circle skirt in inches, use the following formula:

waist radius = (waist measurement / 2π) - 0.8

In our case:
waist radius = (30.7/2π) - 0.8 = 4.89 - 0.8 = 4.09 [in]

How do I calculate a 3/4 circle skirt?

To calculate a 3/4 circle skirt:

  1. Measure your waist in cm - W.
  2. Decide on the skirt's length in cm - L.
  3. Use the formula R = 4/3 × W / 2π - 2 to calculate R – waist radius.
  4. Use the formula FL = L + R + 2 to count FL – fabric length.
  5. Remember all the measurements are in centimeters – cm.
  6. That's it!

How do I calculate measurements for a circle skirt?

To calculate measurements for the circle skirt:

  1. Measure your waist in cm – W
  2. Plan the skirt's length in cm – L
  3. Now use the proper formula, depending on the skirts type:
  • Full circle: R = W / 2π - 2;
  • 3/4 circle R = 4/3 × W / 2π - 2;
  • 1/2 circle R = 2 × W/ 2π - 2; and
  • 1/4 circle R = 4 × W / 2π - 2.
  1. Count the fabric length FL with the equation:
    FL = L + R + 2

How do I calculate yardage for a circle skirt?

To calculate yardage for a full circle skirt:

  1. Measure your waist in yd – W.
  2. Decide on the skirt's length in yd – L.
  3. Use the formula R = 4/3 × W / 2π - 0.022 to calculate Rwaist radius.
  4. Use the formula FL = L + R + 2 to count FLfabric length.
  5. Remember all the measurements are in yards (yd).
  6. And you're done!
Bogna Szyk
Full circle skirt
Skirt length
Waist radius
Fabric length
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