Special Sunday greetings you naked molerats! Since you’re so naked, I thought you might want to make yourselves some nice little circle skirts. And perhaps, like me, you find yourself with little mole rat patterns just a touch on the small side. But the grading of a circle skirt isn’t so easy, is it you naked rodents? Oh no, not so easy at all…

OK. Goofing around aside, I’ve been giving myself a headache reviewing geometry, so I made myself a calculator and thought I’d share it! I don’t know about you guys, but the math involved with circle skirts is not immediately apparent to me. I mean, I DO get it, after staring at it for a bit, but my understanding totally vaporizes after a few hours and then I have to study up again.

Recently I’ve been plotting about two separate circle-skirt related issues in my head. First, as much as I love my full circle skirt pattern (Kwik Sew 3637 – here’s my last project using it!) it’s just a bit too, um, full circle. I think I’d like to check out a half or 3/4 circle skirt and see how I like that.

For those unfamiliar with circle skirts, here’s the difference between the three styles. Full circles are full doughnuts, half-circles are half a doughnut – you get the picture. Whether you have a full doughnut or a half doughnut, the inside of the doughnut is the same length as your waist measurement. The green circle on each drawing below marks the waist measurement. So if your waist is, say 30″, then that green line is 30″ long in each drawing, but the full circle skirt has twice the volume of the half circle skirt. Get it??

For a much more interesting comparison, here’s a full circle skirt. In action.

{image Whirling Turban}

Here’s the oh, so lovely three-quarter circle skirt.

{image Whirling Turban}

And a slightly pixelated half circle skirt…

{image Get Go Retro}

The other circle-skirt related problem I’ve been mulling over has to do with grading up circle skirts (i.e., making the skirt larger than the pattern I’m using.) Since I usually start with a size 18 pattern (in the big 4 sizing) and do an FBA to get the bust to fit, I also have to grade up the skirt as well. To properly grade a circle skirt, one needs to move the waistband DOWN, not add width to the pattern piece! Here’s what I mean…

OK, I admit I usually grade up my circle skirts the ‘wrong’ way. It works, but it makes the bias hang super-extra weird! My problem was I didn’t know how much to move the waistline down to add the inches I needed, as there’s all kinds of geometry involved!

My problem is (hopefully) solved! I studied helpful posts from other smart folks on the internet and practiced the equations in Excel so that I’d have a handy calculator and won’t have to remember what the difference between the radius and diameter is anymore and how pi fits in to all of this. 

In fact, it’s so handy, I’m sharing with you all!


The Circle Skirt Worksheet

I made two little handy tools  – they both live in the same file – in fact, in the same sheet! The first tool is the Circle Skirt Worksheet. I’ll include a screen shot to go over it, but you can download the non-editable document on Google docs.

Circle Skirt Worksheet + Grading Calculator – Google Sheets Version

In order to better understand the match of a circle skirt, here are the basics involved in drafting this style. To draft a circle skirt (full, 3/4, or half) you need to find out the radius of your waist. I know, whenever I read the word “radius” my eyes roll back in my head (thus the excel worksheet so I don’t have to figure it out anymore…) The radius is the distance from the middle of a circle to the edge. The pink line below shows the radius of that circle.

When you draw a pattern piece for a full and half circle skirt, this is what you’ll end up with. (note! 3/4 skirts are a bit different, I’ll show that in a bit!)

You’ll need four of these quarter-doughnut shapes to make a full circle skirt, two to make a half circle skirt. Obviously, the half circle shapes will have a deeper/longer radius, so it’ll still reach all the way around your waist! I’ll return to my mini-drafting lesson after we take a look at the Circle Skirt Worksheet… here it is.



The white boxes are places where you will enter information, they grey boxes show the numbers you need to draft your pattern piece and correspond to the radius and skirt length measurements in the image above. First, you have to decide what kind of skirt you’re making – full/three-quarter or half – you only use one column at a time. The example is set to make a knee length skirt with a 38″ waist measurement (I use inches, but I think it’ll work the same in the metric system.) Enter your waist measurement in line 5. If you’re starting from scratch you might want to draft for a measurement slightly smaller than your waist measurement, due to the stretching on the bias at the waist. If you do want to adjust down, enter the number of inches to subtract in line 6. I suggested two inches, but Lex from What the Craft suggests four inches in her tutorial. You an also just put a zero in line 6. Once you enter these two numbers you’ll get your waist radius in the grey box in line 8 (5.73 in the full circle example.) At this point, you have enough information to draw the green quarter circle in the image above.

Now it’s time to figure out where to draw the pink line – which is the cutting line for the hem. On line 12 enter the length you’d like your skirt – maybe measure a skirt you have to find out?? Then enter your seam allowance on line 13 – I used a half inch and I only need one seam allowance because I’m just attaching to a waistband. Finally, enter your hem allowance on line 14 – I’m super lazy and do a narrow hem on full circle skirts, but I know lots of people like deeper hems! Line 15 shows the number you need (in the grey box) to draft the pink line which is the hem cutting line. Note – the measurement shown on line 15 is the distance of the hem cutting line from the center of the circle, it’s not just the length of your skirt with the allowances!

To continue the mini drafting lesson – I’ll just include drawings of what the pattern pieces would look like for the full, half and 3/4 circle skirts using the numbers in the example. To draw the curved lines it’ll be more exact if you use a flexible tape measure or some other string-type implement to make a giant compass for yourself. Secure in the center of the circle (lower left corner in the drawings below) with your finger or a pin and secure your pencil at the measurement you’re drawing (i.e. 5.73″ for the waist for the full circle skirt) and draw a nice arc. OK, here goes…

For the full circle skirt you’ll need FOUR of these shapes – if you fabric is narrow enough you can fold into fourths and cut one big circle! Otherwise you’ll have to find some folding combination that’ll get you enough of these – perhaps two cuts on doubled up fabric??

For the half skirt, you only need two of these – it may seem like a lot less, but with the waist radius and hem cutting line so much larger, you’ll still need a lot of fabric!

Since a 3/4 circle skirt is, well, three quarters of a circle, it doesn’t break down nicely into the little quarter circles. I SUPPOSE you could cut a pattern piece the same shape as the ones shown for half and full skirts and then cut three of those, but I’d rather have two seams than three (anyone out there know a better way to do this??) If I was starting from scratch, I’d probably draft the full pattern piece and then fold neatly in half to get half a skirt. Fold in half again and it’d be the right size for cutting on a double layer of fabric…

To draw full size, start out by drawing two lines at 90 degree angles (see grey lines below) that are the length of your hem cutting line measurement from line 15 of the calculator. Then make your giant string compass to draw the hem cutting line (pink) and the waist radius (green) from the corner of your two lines.

Let’s move on to grading, shall we??


The Circle Skirt Grading calculator

Whew! I did NOT intend to cover all of that!! Really, what I was interested in was resizing an existing pattern, but, as you’ll see, it was necessary to put together the Circle Skirt Worksheet in order to figure out how to grade! Please visit What the Craft and Kadiddlehopper for more detailed pictures regarding pattern drafting, cutting and the rest!

I like to start with a commercial pattern and alter – and as I said above, altering a circle skirt takes some math skills! I knew I had to deepen that waist cutting line to make my commercial pattern bigger, but I didn’t know how much. What I came up with is more of a worksheet than a calculator – you’ll need to use the Circle Skirt worksheet to complete the grading worksheet! Here’s a look at it – again, you can also view in Google docs. And also again, click the image to see larger.

OK! This is super easy to use. First, enter the pattern’s waist measurement in the field on line 20. In the example moving from a 36 to a 42 inch waist. Next, use the Circle Skirt Worksheet to calculate the waist radius (line 8 ) for the pattern waist measurement and enter that in line 20. Next, enter your new waist measurement in line 22 and calculate the waist radius and enter in line 23. Voila! Line 24 shows how much to move your waist and hem cutting lines down – obviously you’ll have to add tissue to the hemline! Also obviously, you could just use the Circle Skirt worksheet to figure out those waist radii and subtract in your head. Or, perhaps YOU could, I can’t. I’m terrible with math-in-my-head!!

There we have it! I hope it’s helpful to someone (other than me!!) Clever readers may note that there aren’t seam allowances included if you cut the skirt in multiple pieces, but honestly, with circle skirts you’re working on the bias which allows enough stretch to fudge those!

And as always, any of you geometry and/or pattern drafting eggheads, feel free to chime in with corrections to my equations, methods, etc!!

And with that, I’m off. Expect to see some basset hound-sized circle-tutu’s in the near future!


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