How to calculate circle skirt radius/Detailed explanation on how to cut circle skirt.

Summary

In this 'All About Sewing' lesson, the instructor teaches viewers how to calculate the radius for different degrees of circle skirts, including 360, 270, 180, and 90-degree styles. The key formula involves dividing the waist measurement by 6.28, with adjustments for skirt degree and fabric stretch. The tutorial simplifies the math, making it accessible for sewing enthusiasts to create full, half, quarter-circle skirts, and more, with practical tips for fabric cutting and fitting.

Takeaways

• 📐 The lesson focuses on calculating the radius for different types of circle skirts using specific formulas.
• 🧵 For a 360-degree full circle skirt, the radius is found by dividing the waist measurement by 6.28.
• 🔄 The 360-degree skirt forms a full circle, with the radius being the distance from the waist to the hem.
• ✂️ To get a perfect fit for non-stretch fabric, subtract 2 inches from the waist measurement before dividing by 6.28.
• 📏 A 270-degree skirt uses a similar method but with an additional factor of 1.33 in the formula.
• 💡 The 1.33 factor comes from dividing three-quarters of a full circle (3/4) to adjust the formula for a 270-degree skirt.
• ➗ For a 180-degree half-circle skirt, divide the waist measurement by 3.14 to find the radius.
• 🔍 The 180-degree formula simplifies the full circle formula by considering half of the circle's circumference.
• 🔄 A 90-degree quarter-circle skirt requires multiplying the waist measurement by 2 and dividing by 3.14 to find the radius.
• 🧮 Each formula is derived from the basic concept of calculating the circumference of a circle, adapting it to different skirt designs.

Q & A

What is the primary focus of the 'All About Sewing: Circle Skirt Lesson One'?

The primary focus of the lesson is to teach the mathematics involved in creating circle skirts, specifically the formula for calculating the radius needed for different degrees of circle skirts.

What is the formula used to calculate the radius for a 360-degree circle skirt?

For a 360-degree circle skirt, the formula to calculate the radius is to divide the waist measurement by 6.28.

Why might you need to subtract 2 inches from the waist measurement when sewing a stretch fabric circle skirt?

You might need to subtract 2 inches from the waist measurement when sewing a stretch fabric circle skirt to ensure a perfect fit around the waist without needing any side or back seams or zippers.

What is the significance of the number 6.28 in the context of the sewing lesson?

The number 6.28 is used in the formulas because it represents two times pi (2π), which is the constant used to calculate the circumference of a circle.

How does the formula for a 270-degree circle skirt differ from that of a 360-degree skirt?

For a 270-degree circle skirt, the waist measurement is multiplied by 1.33 and then divided by 6.28, as opposed to just dividing by 6.28 for a 360-degree skirt.

What mathematical concept is used to derive the radius for a 180-degree circle skirt?

The radius for a 180-degree circle skirt is derived by dividing the waist measurement by 3.14, which is half of 6.28, representing half of the full circle's circumference.

Why is the number 3.14 used in the formula for a 180-degree circle skirt?

The number 3.14 is used because it represents π, and since a 180-degree circle skirt is half of a full circle, the formula uses half of 6.28 (which is 2π).

What is the formula for calculating the radius of a 90-degree circle skirt?

For a 90-degree circle skirt, the formula is to multiply the waist measurement by 4 and then divide by 6.28, or alternatively, divide the waist measurement by 3.14 after considering the full circle formula.

How does the instructor explain the transition from the full circle formula to the half and quarter circle formulas?

The instructor explains the transition by demonstrating how the full circle formula is adjusted by dividing by 2 for the half circle (180 degrees) and by 4 for the quarter circle (90 degrees), reflecting the proportional parts of the circle being used.

What additional advice does the instructor give for cutting out the circle skirt pieces from the fabric?

The instructor advises that for non-stretch fabrics, the material should be folded into four to cut out the circle, and for stretch fabrics, one might need to adjust the waist measurement accordingly to avoid seams or zippers.

Outlines

00:00

🧵 Introduction to Circle Skirt Math

This paragraph introduces the concept of sewing a circle skirt, focusing on the math needed to cut the skirt correctly. The instructor reassures viewers that the math is simple and involves a specific formula for dividing the waist measurement to find the radius, which is crucial for cutting the skirt. The example given is for a 360-degree circle skirt, also known as a full circle skirt, where the radius is calculated by dividing the waist measurement by 6.28. The paragraph also touches on considerations for stretchy and non-stretchy fabrics and the potential need for subtracting two inches from the waist measurement for a perfect fit.

05:01

📏 Calculating the Radius for a 360-Degree Circle Skirt

This section dives into the calculation of the radius for a 360-degree circle skirt, using a basic mathematical formula. The circumference of the circle is represented by the waist measurement, and the radius is derived by making it the subject of the formula. The instructor explains that the circumference is equal to 2πr (where π is 3.14), and by rearranging the formula, the radius is found by dividing the waist measurement by 6.28. The explanation is reinforced by reworking the formula step-by-step, clarifying how this math is applied in the context of sewing.

10:03

🔄 Understanding the 270-Degree Circle Skirt

This paragraph discusses the 270-degree circle skirt, highlighting the difference in its formula compared to the 360-degree skirt. The main distinction is the introduction of a factor of 1.33, which comes from dividing the circle into four parts and using three of those parts. The instructor explains how this factor alters the formula, which now requires multiplying the waist measurement by 1.33 before dividing by 6.28. The instructor also promises further explanation in a later lesson, particularly regarding the practical aspect of cutting a 270-degree circle skirt.

15:06

➗ Calculating the Radius for a 180-Degree Circle Skirt

This section covers the 180-degree circle skirt, where the full circle is divided into two halves. The formula to calculate the radius for this type of skirt is slightly modified: the waist measurement is divided by 3.14 instead of 6.28. The instructor provides a detailed mathematical explanation, showing how the full circle formula is adapted by dividing both the numerator and denominator by two, leading to the simplified formula used for the 180-degree skirt. The importance of understanding this change in the formula is emphasized.

🔢 Formula for a 90-Degree Circle Skirt

The final paragraph discusses the 90-degree circle skirt, which is essentially a quarter of a full circle. The radius for this skirt is calculated by dividing the waist measurement by 3.14 after adjusting the full circle formula. The instructor explains how the full circle formula is adapted by multiplying the waist measurement by four and then dividing the result by 6.28, which simplifies to dividing the waist measurement by 3.14. The instructor reassures viewers that these formulas are easy to understand and will be further demonstrated in upcoming lessons.

Keywords

💡Circle Skirt

A circle skirt is a type of skirt that is shaped like a circle, providing a full, fluid silhouette when worn. In the video, the instructor focuses on teaching how to calculate and cut fabric for a circle skirt, which is central to the theme of the lesson.

💡Skirt Math

Skirt Math refers to the calculations required to determine the necessary fabric dimensions for creating a circle skirt. The video emphasizes that understanding these mathematical formulas is crucial for sewing a circle skirt, making it a key concept.

💡360 Degree Circle Skirt

A 360-degree circle skirt is a full circle skirt that covers the entire circumference of the waist when worn. The video explains the formula for calculating the radius of fabric needed for this type of skirt, highlighting it as an important step in the sewing process.

💡Radius

In the context of the video, the radius refers to the distance from the center of the circle (waist) to the outer edge of the fabric. The instructor teaches how to calculate the radius using waist measurements, which is essential for cutting the fabric correctly.

💡Waist Measurement

Waist measurement is the circumference of the waist, which is a critical starting point for all calculations in sewing a circle skirt. The video script provides detailed instructions on how to use waist measurement in the formulas for different types of circle skirts.

💡Non-Stretch Fabric

Non-stretch fabric is mentioned in the video when discussing adjustments to waist measurements for certain types of circle skirts. The instructor notes that for non-stretch fabrics, an additional two inches may be subtracted from the waist measurement to ensure a proper fit.

💡Stretch Fabric

Stretch fabric is discussed in relation to how it affects the sewing process, particularly when it comes to fitting the skirt around the waist. The video mentions that for stretch fabrics, the two-inch deduction from the waist measurement may not be necessary.

💡Joining

Joining refers to the process of sewing two pieces of fabric together, such as at the side or back of a skirt. The video script explains that if there is a joining, the two-inch deduction from the waist measurement may not be required, as the fabric can be adjusted at the seams.

💡Zip

A zip, or zipper, is mentioned in the context of the back of the skirt, where it might be used for closure. The video explains that if a zipper is used, it might affect the waist measurement calculations, as the fabric can be adjusted at the zipper.

💡270 Degree Circle Skirt

A 270-degree circle skirt is a semi-circle skirt that covers a portion of the waist circumference. The video provides a formula for calculating the radius of a 270-degree skirt, which is a variation of the full circle skirt and part of the sewing lesson.

💡180 Degree Circle Skirt

An 180-degree circle skirt is a half-circle skirt, which covers half of the waist circumference. The video explains the formula for calculating the radius of this type of skirt, which is a key part of the sewing lesson and an alternative to the full circle skirt.

Highlights

Introduction to the circle skirt lesson focusing on skirt math.

Explanation of the formula for a 360-degree circle skirt, also known as a full circle skirt.

The importance of calculating the radius for cutting the skirt.

How to divide the waist measurement by 6.28 to get the radius for a 360-degree skirt.

Instructions for adjusting the waist measurement for stretch fabrics.

The difference between waist measurement adjustments for stretch and non-stretch fabrics.

Visual demonstration of the full circle skirt's shape and fit.

Introduction to the 270-degree circle skirt and its formula.

Explanation of the 1.33 multiplier in the 270-degree skirt formula.

The 180-degree circle skirt's formula and its relation to the full circle.

How to calculate the radius for a 180-degree skirt using waist measurement divided by 3.14.

Introduction to the 90-degree circle skirt and its formula.

Calculation method for the radius of a 90-degree skirt using waist measurement divided by 3.14.

Overview of the four types of circle skirts: 360, 270, 180, and 90 degrees.

The significance of the number 6.28 in the formula and its relation to pi.

A brief explanation of the mathematical formula for the circumference of a circle.

How to derive the radius formula from the circumference formula.

Conclusion and invitation for questions, signaling the end of the lesson.

Transcripts

hi everyone welcome to all about sewing

circle skirt lesson one in this lesson

i'm going to teach you second skirt math

so a lot of people

math is just like doing a magic but

trust me it is really really easy all

you need to know is the formula for a

particular skirt you're cutting so for

example you're cutting a 360 degree

circle square you need to know what to

use to divide your waist measurement to

get the radius for you to be able to cut

the skirt so let's get started

for

360

the grey sapper skirt which is also

known as a full circle skirt of fufule

which is

like this

there's a full round circle so here you

have to get your radius

this from this point to this point is

the radius so the full

middle part here is the diameter but all

we need to know is the radius which is

from the middle to the end point here so

this is going on the waist

and this is the lower part of the skate

so here when you fold your material into

four so all you need to do is from this

tip

all around to get the radius for you to

be able to cut out this little circle

inside

for this part to go on the waist so for

360

circle

skirt

to get your radius you have to do

your waist measurement let me use m to

represent measurement your waist

measurement divided by

6.28

so this is what you use to get the

radius here to be able to cut out the

little

circle inside so this is on the lower

part of your skin and this is going

around your waist

note that

on this part of your skin is stretchy

even for non-stretch fabric so if you

don't want to have any joining on the

side or on the back for zip if it's a

stretch fabric you need to minus two

inches

from your waist measurement

here so

to have that perfect fit around the

waist so you need to minus two from your

waist measurement but if you're having a

joining maybe on the side or on the back

side for zip you don't have to minus

this two inches

from your waist measurement

so

here this is how the skate looks like

it's very full

and it goes like

it's very very very full

goes like this so this part is what we

have here in the middle so it's just

like a circle

so this is 360 degree second square

which is a full circle scale so we have

three more we have the 270 degree we

have the 180 degree and we also have the

90 degree so which makes it

four types of

circle skate we have and the most common

ones is always the 360 and a 180

so remember that this two inches you're

deducting from your waist measurement is

before dividing with the 6.28

so

if you're if you're not for example if

say you're joining on the side or at the

back you don't have to

minus this

to from your waist measurement so you

just use your waist measurement divided

by 6.28 so if you care to know how this

6.2 a

came into this formula

so this is a circle and the second

friends of the circle that is the

measure around the circle

so the second french of this little

circle we are cutting out equals two pi

r so that is the math formula of finding

the circumference of a circle so

basically this is a circle and we want

to know the radius here

so this is the radius

so pi is always this is constant is

always 3.14 or 22 over seven so

this is pi and it's constant

here

okay sorry brother okay so set the

second friends of the circle will be two

multiplied by this three point one eight

it won't force sorry three point one

four

multiply by this r you're having here

okay

so

let me erase this

okay

so here

i have 2 multiplied by 3.14 that will

give me

6.28

so c equals

6.28

then remember this r

so now

we're looking for the r

so we need to make this r the subject of

this formula

so here i have the r i'm bringing a har

as the subject of the formula so i'm

dividing both sides if i divide both

sides by two point six point two eight

divided by six point two eight so this

six point two eight is going to cancel

this this is just a basic max don't get

confused so you're left with r here

then equals the c

which is the circumference of the circle

divided by

6.28

so this is just a basic mass so

this c is represent this c is the

circumference of this circle which is

the same as our waist measurement so

that is why

in this formula

the c here is replaced with this the

waist measurements divided by the same

6.28

i hope you understand that but let me

quickly go over it again so this is the

second friends of the circle the little

circle we are cutting out from the scale

to go on the waist

so that is circumference of the circle

so which is c to represent the second

friend equals two pi r this is the

formula of finding of circumference of a

circle so here pi is always

3.14

okay so i replace this pi with 3.14 here

so 2 multiplied by 3.1 for r

so i have it here to be 2 multiplied by

3.14 so that gave me 6.28

then i

i put in this heart here so i have c

equals that is the circumference of the

circle equals

6.28 multiplied by the radius

so here how can i make the r the subject

of the formula so here what i'm going to

do is divide both sides by 6.28 because

i want to get rid of this 6.28 beside

the heart and make this r stand alone

so when i divide when i divided both

sides by 6.28 this 6.28 i have here

cross out the 6.28 beside the r so i'm

left with c over 6.28 equals r which is

the same thing as r

as the radius equals circumference

divided by 6.28

and this is replaced with waist

measurement because that is the part

that is going on

the waist

the next one is 270 degree

second skirt

okay so 4270 as i mean i have a line

going through the side so i have just

this spot

for the 270.

so guys

before we have 360. that's 1990 9090 so

990 is 180 then close the

other 90 degree we have

270

so here

yes so the radius is just going to be

from here

to this side

like this one

okay so that is for 270 degree

circle

skirt

okay

so here

it's very similar to the full one the

difference is just this back so

here i have

the radius to be

1.33

multiplied by your waist

measurement

then divided by

6.28 so the only difference we have here

is just this

1.33

so if you can't know how is 1.33 came

into this formula so we have this is

just

three over four

so which is if i divide this the former

circle into four i have one

two three four so now i'm having three

out of four that is three over four

so now you're dividing your waist

measurement

by three over four

here and then when you multiply

this way

this changes so the denominator comes up

and

the numerator goes down that is the

basic mass don't worry yourself too much

about this so you have your waist

multiplied by

4 over 3 and when you calculate 4 over 3

you have

1.33

so that is how this 1.33 came into this

formula by dividing 4 into 3

so that is 1.33 so after calculating

this for your radius

you're doing that for the old circle

after which you have to remove one out

of

those four

i'll explain more on this how you can

cut this to 270 degree circle scale in

the for of i think thought lesson yeah

or the thought lesson

so that is that about 270 degree this is

just the difference in the formula from

the previous one we had

so that this is the 270 degree formula

moving on to 180 degrees circle

so 180 degree

circle skirt

okay

so here we are dividing the whole this

is let me draw the full circle again so

we are dividing this full circle into

two

so

so the radius i'm having from here to

here or from here to here

so this is just the radius here

so from

here to here

okay

so

for this 180 degree

circle skirt

remember for the full one we had a

circumference equals

the waist measurement divided by

6.28

okay but here this

full circle is divided by two that is

half

of the full

second friends we had

okay so here

that is

we divided the circumference into two so

now to get the formula for this 180 we

need to multiply it by the

circumference to get this part of the

circle

if we want to divide

we want to use the circle the

circumference formula so here

when we want to multiply this as usual

the denominator comes up and the

numerator comes down that is 2 over 1

and 2 over 1 is same thing as 2.

multiply by the waist

then

that would be divided by 6.28

let me do that again

so for the 180 here

i have

the radius equals

to

multiply by

the waist

measurement

then divided by

6.28

this

still the number

the waist measurement divided by two

6.28 we had in the previous step

so the only difference

on this

180 degree is that

you have

two of this f

in the o circle

so this is still the formula of the full

circle but this is just telling us that

we have two of this

on the half so

when

you cross half two goes here in one and

six point two eight divided by two you

have three point

one four

so if you didn't really get that don't

worry this is just a basic maths so it's

just that i'm dividing i have to hop

here and i have 6.28 here so instead of

repeat repeating this like saying my

waist measurement multiply by two and

divide this which i know i can divide

this

6.28 by two and get rid of those two i

have on the upper part here so it's just

basically saying i divided this by two

and also i divided this by two so here i

have

these two is gone so i have my waist

measurement

sorry

so here i have my waist measurement

divided by 3.14

so if you don't really understand these

steps just note that

for 180 degree circle scale

to find the radius you're using your

waist measurement

divided by 3.14

so the explanation i did earlier is just

for you to understand how this

3.14 was changed from the number 6.28 we

use for the full circle that is because

we have this half circle twice

in the full circle so that is just the

basic my about 180 degree circle

moving on to 90

degree circle which is the last one

so here

as i mean i okay let me draw the full

circle again

sorry this is not all right okay

so imagine if i want to divide my circle

into four and i'm having just this 90

remember this is 360 and

if i remove one of it that's -90 i have

270

then if i remove one again i'm left with

180 and then if i remove okay let me

remove this part

okay here i'm left with 90 degree

so here this is the little

circle we're cutting half to the radius

we just be from this point down to

so the radius is just going to be from

this point to this point

and this point so this is the eye

here

okay so this is 90 degrees

spirit

okay

so

for this this is just like saying we

divided the whole second friends into

four so to get this

using the we're still using the full

circle formula but we're going to

multiply

out this part by four if we still want

to maintain

the full

circle formula so here if i have

4

[Music]

so basically this is just telling me

that

4 of this will give me the full

circle which i'm using the formula so 4

multiplied by my waist measurement

divided by 6.28

so i'm still using a full circle formula

but this four is

telling me that i have

four of these 90 in the full

circle formula i'm using so i have just

this

as 90 but that would give me four times

this whole circle to be able to get 360

because i'm seizing

here i'm see using the full circle so

this is just like saying

four out of the four circle

so here

like the 180 where i have two up here

and six point two eight a then i divided

both by two so same thing i can divide

by two i can't divide this by four but i

can divide it by two so if i divide four

by two i'm left with two and if i divide

this by two i'm left with three

point one four

so

using this

my radius will be

two remember i have two here

that is i had four before

when i divided by two that gave me

2. so i have to

multiply by my waist

measurement

then divided by not 6.28 this time but

3.14 because i divided both my numerator

here by two and the denominator also by

two so i'm having three point

one four

so this is

the formula for finding the radius of 90

degree

circle skirt

so just take note of all the formulas

they're easy

and

they're very very easy to understand if

you can just

put them in mind and take note of all

the formulas

i'll explain more next lessons how

radius is marked on fabric so when we're

doing the practical of cutting all the

degrees of sacrifice care we have so

that's all for today thank you

and let me know if you have any

questions