After last week’s Bias: Definitive Essential Foolproof Guide post, today I want to go practically: how can I bias cut a rectangle, having only its measurements?

Math is closely related to sewing and I feel like a lot of self-taught sewists try to skip this part, but I think it’s a huge mistake: math is FUN – and I’m going to teach you a quick and practical trick!

Let’s talk about Pythagoras Theorem!

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

One of the features of The Sheer Plaid Top (my first pattern to be sold – actually under testing – release date February, 1st) is a softly draping collar, bias cut without a pattern piece, only having its measures…

I received so many questions about how to do that, that I realized it wasn’t as obvious as I though!!

Let’s clarify, and I hope that, when you’re finished reading this post, you’ll catch how easy is to bias cut a rectangle!

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Bias Cut – Practical Trick

As we know that bias is at 45 degrees to a fabric’s warp and weft threads, then we can use Pythagorean’s  rules about triangles!

Look at my example photo: as you can see, my meter stick (a 24″ quilter’s ruler is perfect for this task) is placed exactly along the bias (hypotenuse of our right-angle triangle isosceles), because the width (A) and the height (B) of the same triangle (where I put my two measure tapes) are the same length.

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

The fun part is that, if you know your hypotenuse length (= our bias length), you can calculate width (A) and height (B) with this easy formula:

formula

where square root of 2 is ALWAYS 1.4142135

…wait… what?

Ok, let’s simplify for those who don’t eat bread and math for breakfast!

Our example bias piece will be 25 cm long, 3 cm height, so:

  1. Measure from your fabrics angle between crosswise direction (A) and selvedge (B) the same measurement, that is:

25/1,4142135= 17,7 cm

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras) 

  1. Fold your fabric along the bias line (you can help yourself with some pin, of a chalk line…)

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

 and cut along that fold!

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

  1. Measure desired height perpendicularly to the bias (3 cm in our example). Here too you can proficiently use your quilter ruler to trace a line 3 cm far from the bias cut.

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

and cut again!

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

  1. Finally, cut out your strip heads, just to have a rectangular (and not trapezoidal) shape:

Serger Pepper Tutorial: Bias Cut: Lifesaver, Quick & Practical Trick (feat. Pythagoras)

 That’s it!

Is that hard to do? Not really…

Hard to remember? You don’t have to, simply… just pin this post 🙂

Serger Pepper - Cut on Bias - How exciting is this math trick (feat. Pythagoras) ok

That’s all for today, stay tuned to discover what comes next… or learn how to design your own clothes… on the bias!

 

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