# Please help me with my math

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**11**Super Member

Join Date: Feb 2013

Posts: 1,340

Too.Many.Numbers...I'm so glad there are others here that aren't put off by the math portion of quilting!

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**12**Power Poster

Join Date: May 2009

Location: NY

Posts: 10,568

Not to throw a monkey wrench into the works, but sashing around all 4 sides of the block is exactly how I do it. That way all I have to do is sew the finished blocks into rows and match the seams at the corners. Takes the headache out of making sure the rows all line up perfectly on long rows of sashing.

So I think she is still quite safe with 2 yards of fabric for the sashing whichever way she decides to sash. IMHO when doing corner stones it is very easy to line the strips up when assembling the quilt. Order an extra yard just to be safe or in case she decides to use the sashing fabric as binding as well.

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**13**Senior Member

Join Date: Mar 2011

Posts: 767

Here's I do the math:

for a 8 x 10 layout with sashing going around the outside

9 vertical sashing strips per row X 10 rows = 90 vertical sashing strips

11 horizontal rows of sashing (includes the top/bottom outside edges) x 8 strips / row = 88 horizontal sashing strips

90 vertical + 88 horizontal =

Is the 4" square finished (cut at 4 1/2") or unfinished (finishes at 3 1/2")?

Assuming that the 4" square is the finished size (cut at 4 1/2"):

Each sashing strip needs to be cut at 4 1/2" x 2 1/2". You can typically get nine 4 1/2" strips per width of fabric (assuming usable width of fabric is at least 40.5").

178 strips / 9 strips / wof = 19.77777 --> so

Each sashing strip needs to 2 1/2" wide (assuming 2 1/2" is the unfinished measurement and they are finished at 2")

2 1/2" / wof * 20 wof =

50" / 36" / yd = just a tiny smidge over 1 3/8 yard, so get a

As for the cornerstones, you will need 99, not 90. (11 rows of horizontal sashing with 9 cornerstones per row).

At 2 1/2" cut size, you can typically get 16 squares per WOF (assuming at least 40"). You need 7 rows of fabric to cut the 99 squares. At 7 rows of fabric by 2 1/2" in width, you need just a smidge under 1/2 yard, which I would round to

Good luck!

for a 8 x 10 layout with sashing going around the outside

9 vertical sashing strips per row X 10 rows = 90 vertical sashing strips

11 horizontal rows of sashing (includes the top/bottom outside edges) x 8 strips / row = 88 horizontal sashing strips

90 vertical + 88 horizontal =

**178 sashing strips needed**.Is the 4" square finished (cut at 4 1/2") or unfinished (finishes at 3 1/2")?

Assuming that the 4" square is the finished size (cut at 4 1/2"):

Each sashing strip needs to be cut at 4 1/2" x 2 1/2". You can typically get nine 4 1/2" strips per width of fabric (assuming usable width of fabric is at least 40.5").

178 strips / 9 strips / wof = 19.77777 --> so

**20 wof are needed**to cut the 178 sashing strips.Each sashing strip needs to 2 1/2" wide (assuming 2 1/2" is the unfinished measurement and they are finished at 2")

2 1/2" / wof * 20 wof =

**50" of sashing fabric needed**to cut 20 strips at 2 1/2", with each strip making nine 4 1/2" x 2 1/2" sashing pieces.50" / 36" / yd = just a tiny smidge over 1 3/8 yard, so get a

**minimum of 1 1/2 yards of sashing fabric**As for the cornerstones, you will need 99, not 90. (11 rows of horizontal sashing with 9 cornerstones per row).

At 2 1/2" cut size, you can typically get 16 squares per WOF (assuming at least 40"). You need 7 rows of fabric to cut the 99 squares. At 7 rows of fabric by 2 1/2" in width, you need just a smidge under 1/2 yard, which I would round to

**5/8 yard cornerstone fabric**.Good luck!

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**14**Super Member

Join Date: May 2011

Location: Pacific NW

Posts: 7,928

But when you do this I would have to think that you must reduce the width of your sashing strips to half of what you would use if sashing in the more tradtional aspect. In the OP's example surely she would not sash 4" blocks with 2" (finished) strips on all 4 sides, That would make the finished size of the sashing the same size of the blocks completely defeating the look of sashing and making it look more like alternate unpieced blocks.

So I think she is still quite safe with 2 yards of fabric for the sashing whichever way she decides to sash. IMHO when doing corner stones it is very easy to line the strips up when assembling the quilt. Order an extra yard just to be safe or in case she decides to use the sashing fabric as binding as well.

So I think she is still quite safe with 2 yards of fabric for the sashing whichever way she decides to sash. IMHO when doing corner stones it is very easy to line the strips up when assembling the quilt. Order an extra yard just to be safe or in case she decides to use the sashing fabric as binding as well.

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**15**Senior Member

Thread Starter

Join Date: Jul 2012

Posts: 415

Wow, thank you! That's so helpful!

Quote:
Here's I do the math:

for a 8 x 10 layout with sashing going around the outside

9 vertical sashing strips per row X 10 rows = 90 vertical sashing strips

11 horizontal rows of sashing (includes the top/bottom outside edges) x 8 strips / row = 88 horizontal sashing strips

90 vertical + 88 horizontal =

Is the 4" square finished (cut at 4 1/2") or unfinished (finishes at 3 1/2")?

Assuming that the 4" square is the finished size (cut at 4 1/2"):

Each sashing strip needs to be cut at 4 1/2" x 2 1/2". You can typically get nine 4 1/2" strips per width of fabric (assuming usable width of fabric is at least 40.5").

178 strips / 9 strips / wof = 19.77777 --> so

Each sashing strip needs to 2 1/2" wide (assuming 2 1/2" is the unfinished measurement and they are finished at 2")

2 1/2" / wof * 20 wof =

50" / 36" / yd = just a tiny smidge over 1 3/8 yard, so get a

As for the cornerstones, you will need 99, not 90. (11 rows of horizontal sashing with 9 cornerstones per row).

At 2 1/2" cut size, you can typically get 16 squares per WOF (assuming at least 40"). You need 7 rows of fabric to cut the 99 squares. At 7 rows of fabric by 2 1/2" in width, you need just a smidge under 1/2 yard, which I would round to

Good luck!

for a 8 x 10 layout with sashing going around the outside

9 vertical sashing strips per row X 10 rows = 90 vertical sashing strips

11 horizontal rows of sashing (includes the top/bottom outside edges) x 8 strips / row = 88 horizontal sashing strips

90 vertical + 88 horizontal =

**178 sashing strips needed**.

Is the 4" square finished (cut at 4 1/2") or unfinished (finishes at 3 1/2")?

Assuming that the 4" square is the finished size (cut at 4 1/2"):

Each sashing strip needs to be cut at 4 1/2" x 2 1/2". You can typically get nine 4 1/2" strips per width of fabric (assuming usable width of fabric is at least 40.5").

178 strips / 9 strips / wof = 19.77777 --> so

**20 wof are needed**to cut the 178 sashing strips.

Each sashing strip needs to 2 1/2" wide (assuming 2 1/2" is the unfinished measurement and they are finished at 2")

2 1/2" / wof * 20 wof =

**50" of sashing fabric needed**to cut 20 strips at 2 1/2", with each strip making nine 4 1/2" x 2 1/2" sashing pieces.

50" / 36" / yd = just a tiny smidge over 1 3/8 yard, so get a

**minimum of 1 1/2 yards of sashing fabric**

As for the cornerstones, you will need 99, not 90. (11 rows of horizontal sashing with 9 cornerstones per row).

At 2 1/2" cut size, you can typically get 16 squares per WOF (assuming at least 40"). You need 7 rows of fabric to cut the 99 squares. At 7 rows of fabric by 2 1/2" in width, you need just a smidge under 1/2 yard, which I would round to

**5/8 yard cornerstone fabric**.

Good luck!

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