Mathing the Yardage II

Last week we worked through the first three steps of estimating yardage for a quilt. This week we will go through the steps of calculating the amount of fabric needed for the rest of the quilt.

Step Four – Sashing Yardage and Quilt Setting

At this point, some design decisions will have to be made.  Will I use sashing?  If I do decide to use it, how wide will it be?  Will I use cornerstones?  If so, what kind of cornerstones will I use?  Will I set the quilt in horizontal rows or on-point?

Birds in the Air Quilt — no sashing or cornerstones

While the answers to some of these questions depends on how I want the quilt to look, some of them also depend on the quilt’s usage.  How big do I need the quilt to be?  If I have 20 Birds in the Air blocks that finish at 9 inches, and plan on setting the quilt in rows, I will have five rows with four blocks in each horizontal row. Without sashing, this means the quilt top will be 36-inches wide and 45-inches long – which makes it a great size for a crib quilt or play quilt, but not very practical for an adult.  It appears, if I stick with the horizontal setting, I need to plan on adding some sashing.

Using the Golden Ratio, we multiply 9-inches x 1.618 and get 14.562

Since there are four sides to a block, we divide 14.562 by 4 and get 3.6405 which comes to 3 5/8 in fraction form.  This mean the widest we can make the sashing is 3 5/8 inches.  Anything larger will look disproportionate. 

I would be the first to admit that 3 5/8-inch sashing is pretty wide sashing in my quilting world.  However, if I had a quilting pattern in mind for these units that would really show off the quilt, I would use the width to my advantage.  Likewise, I’d use that width if I planned on piecing my sashing.  And if I make my sashing that wide, this means my top will be 55 3/8-inches wide and 66 ¾-inches long.  Depending on the width of the borders and how many I decide to use, the top’s width and length could increase as much as 8-inches both ways (63 3/8 x 74 ¾).

Now let’s take it to the other extreme – how narrow could we make the sashing?  For this we take 9 and multiply it by .618.  When we do this, we get 5.562.  Again, we divide this number by 4 and come up with 1.3905 or 1 3/8-inches.  The narrowest we could make the sashing and it still be proportional is 1 3/8-inches.  If we use this measurement, the center would be 42 7/8-inches wide x 53 ¾ -inches long.  Add a possible 8-inches for borders and we would have a quilt 50 7/8-inches x 61 ¾ -inches. 

If neither of the smallest or  largest heights and widths work, remember you can always use any number between the largest and the narrowest widths.  So, if you want to use 2 ½-inch sashing, it will look fine.  Three-inch sashing is your thing?  Go for it.  Four and a half inch sashing?  Nope.  It’s larger than 3 5/8-inches.  Likewise, with my favorite 1-inch sashing.  It’s too narrow.

Since I want my quilt to be large enough for an adult, I will use 3-inch sashing.  Why didn’t I go with the largest number?  Convenience, really.  While mathematically I don’t mind working with difficult fractions or decimals, when I’m cutting out fabric, fractions like 7/8 and 5/8 are harder to cut accurately because my 58-year-old eyes have a hard time seeing those tiny lines on my cutting mat.  Go large or go home.  The 3-inch sashing falls between the largest and the narrowest widths, so it will look fine.   

Let’s look at my layout at this point.

Since I’ve decided on 3-inch sashing, I know that those units will need to be cut at 3 ½-inches to allow for seam allowances.  I will need a total of forty-nine 9-inch units that are 3 ½-inches wide, unfinished. Again, let’s work with forty inches of usable WOF.  When we were working with the triangles, we were adding 7/8-inches to the finished size to allow for seam allowances.  This time we will need to add a ½-inch to allow for ¼-inch seam allowances. We divide 40 by 9 ½ and get 4.2 – we can get four 9 ½-inch units per 3 ½-inch wide strips.  Now, we divide 49 by 4, to determine how many 3 ½-inch strips we need – which comes to 12.25.  We will need to round that up to 13.  Multiply 13 by 3 ½ and we have 45.5 inches or 1 ¼-yard.  If the plan is to use any of the fabrics used in the triangles, add the 1 ¼- yard to that material on the chart.

If cornerstones are in my plan, now I have to figure those now.  They’ll be 3 ½-inches square, and I’ll need 30.  Working with 40-inch WOF again, divide 40 by 3 ½-inches to get 11.42857, which means we need three 3 ½-inch strips of fabric to get all 30 cornerstones.  Multiply 3 x 3 ½ and that’s 10 ½-inches, or 1/3-yard.  If those are coming out of any of the fabric I’ve got on my chart, I need to add it to that yardage. 

My fabric requirements up to this point.

An on-point layout would require a different number of blocks and borders.  Although the math is easy, there is quite a bit of it.  I will cover on-point layout fabric requirements in a follow up.

Step Five – Border Yardages

Borders are wonderful things.  They can pull the quilt top together by color and they can adjust the size of the quilt top.  Quilts with only one border is one of my pet peeves.   I’m not sure why, but it bothers me – even if the border is beautifully pieced and appliqued. 

  1.  Determine how many borders you want to use and the size of the borders.  Let’s go back to my Birds in the Air quilt top.  Per my usual preference, I will add two borders to this quilt top – a narrow first border, and then a wider final border.  And for the sake of illustration, I’m working with primarily plain borders, but I will add cornerstones to the outer border for interest.   
  2. The next thing that should be determined is how I want to cut the borders – do I want to cut them on the straight-of-grain (length of fabric), or do I want to cut the across the width of fabric? Again, for the sake of illustration with this blog (and since it’s the way most quilters make borders), we’re working with WOF. 
  3. At this point, my quilt top is 51-inches wide x 66-inches long.  I need to think of the border like just large quilt blocks.  I want the first narrow border to measure 3-inches wide, so I will cut them out at 3 ½-inches.  Working with 40-inches of usable WOF, I will need to make two cuts per vertical border, for a total of four 3 ½-inch strips.  I can work the top and bottom borders a bit differently.  I can get by with only three 3 ½-inch strips for these.  The math works out like this:  With two cuts, I get a total of 80-inches.  The width of the quilt top is 51-inches.  I subtract 51 from 80 and get a remaining 29 inches.  I can add the left-over fabric 29-inch fabric from the first horizontal border to the remaining third strip and have plenty of material, even with diagonal seam allowances.  So, let’s figure the yardage – this brings the total of 3 ½-inch strips to 7.  When that’s multiplied out, we get 24 ½- inches, or 2/3 of a yard (24.5/36).  I need to add this to my chart. 
This is where the yardage requirements are at now. I will use the green from the large triangles in the block to make my larger outer border and the dark purple from the small triangles for the 3-inch inner border

4. At this point, my quilt now measures 57-inches wide by 69-inches long.  My next set of borders will finish at 5-inches, so I’ll cut those out at 5 ½-inches.  Let’s begin with the left and right borders (I always put my vertical borders on first, and then proceed to the horizontal borders – it was the way I was taught).  Since each side border will measure at 69-inches, and we’re still working with 40-inches of usable WOF, I will need to cut four 5 ½-inch strips.  The top and bottom borders work a little differently, because we’re adding cornerstones.  Normally, I would add the width of the two side borders to the center width of the quilt and get my length of fabric (57 + 5 ½ + 5 ½ = 68)  However, the additional two 5 ½-inch spaces will be filled by 5 ½-inch blocks of different fabrics.  I only need to make the horizontal borders 57 ½-inches long (the ½-inch is the seam allowance), and the sew the cornerstones onto this length to make the top and bottom borders the correct size.  I will need to cut three  5 ½-inch strips to make the horizontal borders.  Just like with the 3 ½-inch borders, I can take the leftover fabric from the first horizontal border I make and add that to the third strip and have enough material.  Let’s do the math:  That’s seven 5 ½-inch strips, which equals out to 38 ½-inches, or 1 yard and 1 ½-inches – or 1 1/8 yards of border fabric.  Add this to the fabric chart.

5. Okay, last border measurement – the cornerstones.  Each cornerstone will need to match the border width, so they will be cut at 5 ½-inches square and we need four of them.  When we multiply 4 x 5 ½, we get 22-inches.  With 40-inches of usable fabric, we know we can get all four cornerstones with one cut.  Divide 5.5/36 and we get 0.152778 or 1/8-yard.  Add that to the fabric chart.

Completed Birds in the Air Quilt

Just a couple of reminders about sewing borders.  Always sew the border strips together on a diagonal, just like you’re making binding.  There is some solid reasoning behind this.  First, a diagonal seam is less noticeable than a straight seam.  Second, it also holds up better to regular wear and tear.  I’ve also been giving you what I call “flat” numbers for this quilt.  We all know there are variances in construction – your needle or fabric will bobble.  Your ¼-inch seams may not stay consistent.  These “flat” numbers are figures done on paper (the paper is flat, therefore, they are flat numbers).  In other words, while fairly accurate, they’re not completely realistic.  Always measure your quilt top in three places both horizontally and vertically.  Take each set of these numbers and get the average.  That number is actually how long you’ll need to make the borders.  If you’re squaring up after every step, the three numbers shouldn’t be off by much.  The “flat” numbers are simply letting you know how much fabric you should plan to use.  And if you’re feeling really fancy and want to miter your borders, you’ll need extra fabric.

The last two steps in estimating the fabric for the quilt top concern the binding and the backing.  After putting on the last set of borders, the quilt should measure approximately 67-inches wide by 79-inches long. 

Step Six – The Binding Yardage. 

I’m working with a couple of assumptions here.  First, we’re using classic French Fold Binding, and second, we’re not cutting the binding on the bias.  Binding measurements work with the perimeter of the quilt — the sum of all four sides.  Simply add 67 + 67 + 79 + 79 to get the perimeter, and this measurement adds up to be 292-inches.  Our binding will need to cover 292-inches worth of quilt.  Binding strips are sewn on the diagonal, and this takes a bit more fabric.  We also will need to leave a “tail” of 10 to 12-inches to allow for joining the binding ends (I always use 12-inches – it’s far easier to cut extra binding off than stop and sew on additional binding). 

Let’s add 15-inches to the 292-inches of binding we know we need.  The extra 15-inches will take care of the additional bit of fabric needed for diagonal seams as well as the “tail” required for joining the binding ends.  This brings the total inches needed to 307-inches.  Divide this by 40-inches of usable fabric and we get 7.675.  Round that up to eight – we need to cut 8 strips of binding.  I always cut my binding 2 ½-inches.  Binding width is a personal preference.  Some quilters cut their binding 2 ¼-inch wide. I’m using 2 ½ with this blog.  I multiply 2 ½ x 8 strips, which equals 20-inches.  Divide 20/36, and I know I need ½-yard of binding fabric.  Usually binding is made from some other fabric that’s been used in the quilt.  Decide which fabric you want to construct the binding from and add the ½-yard to that.  I will make mine out of the fabric I used for the last border. 

Step Seven – The Backing Yardage

Backing is a personal preference issue.  For those quilters who quilt with their checkbook (pay a long or mid-armer for their services), it may not be so personal, but simply boils down to what the long or mid-armer prefers.  However, for those of us who quilt our own quilts, it gets a little more complicated.

With this quilt finishing at 67-inches x 79-inches, it’s well within the range to use the 108-inch quilt backing material.  And I’ll be honest right here – that’s my personal preference.  LeAnne the Long Arm just works better when she doesn’t have to go over a seam.  Big Red doesn’t care.  Neither does my Juki Mid-Arm.  If I need to purchase a quilt backing fabric, I must remember that the width runs along the vertical edge when it’s rolled off the bolt.  The 79-inch edge will be flush with that side of the fabric.  The shorter, 67-inch side will match up with the length of the backing material.  To math-out the yardage, divide 67 by 36.  This comes out to 1 7/8 yard.  The 1 7/8 yard will exactly cover the back.  However, I have to keep in mind since quilts generally draw up a bit in quilting, I need to have some additional margin in both the backing and the batting.  There’s quite a bit of debate among quilters about exactly how much the margin should be.  My personal preference is 6-inches per side.  I add this much because it leaves plenty of margin for my long arm clamps to grip (I baste the top of my quilt, but not the sides – I use the clamps).  So, I will need to add 12-inches to both the length and width of my quilt.  Now my backing needs to measure 79-inches wide by 91-inches long.  I’m still good with the 108-inch wide backing, but I need to divide 91 by 36 to revise my yardage.  That comes out to exactly 2 ½-yards.  If I’m purchasing 108-inch backing fabric, I need 2 ½-yards.  Add that amount to the fabric chart.

But what if (like me) you’re trying to be responsible about your stash and use what you have on hand?  And what if the fabric in your stash is the standard 45-inch wide, cotton quilting fabric?  Well…it’s completely doable, but there’s a little more math involved and some additional pre-planning before you start piecing the quilt back. 

The first step is measure your quilt top.  We know the top we’ve constructed in this blog is 67-inches by 79-inches, and our pieced backing needs to be 79-inches by 91-inches to allow for the quilting margin. 

The second step is picking the fabric.  This is where you can get all kinds of creative.  You can add leftover blocks (one of my favorite ways to piece a back).  You can use any fabric that’s left over from the quilt top.  You can purchase extra fabric.  Just remember the following:

  1.  Solid colored fabric will show up every quilting stitch.  If you’re a proficient quilter or your long arm artist is wonderful, a solid colored backing is great.  However, a “busy” backing can cover a multitude of quilting sins.
  2. There are other fabrics that can be used besides the 100 percent cotton quilting fabric.  Minky and flannel are also great choices and quilt beautifully.  Just be aware that they both are stretchy fabric and minky is so soft and slick it slides all over the place.  After backing my first quilt with flannel, I discovered washing my quilt top before quilting it is a great idea — especially if I didn’t pre-wash my fabrics from the get-go.  The reason behind this is while flannel won’t shrink, a 100% cotton top will.  If I washed the completed quilt, the top would shrink and the flannel back wouldn’t, and that can cause some issues. 
  3. It’s really tempting to use sheets.  They are certainly big enough and less expensive than quilt backing fabric.  I’ve tried using sheets as backing, but haven’t been happy with the results (this was years before I had a long arm – it may work out differently now).  The higher the sheets’ thread count, the more difficult it is to sew.  I have quilting friends that used 100 percent cotton flannel sheets as a quilt backing and loved the results – just be sure to wash and dry the sheets first. 

The third step is consider the seam allowance.  Pieced quilt backs have a larger seam allowance.  The standard ¼-inch seam allowance doesn’t work here.  Seam allowances for pieced quilt backs should be ½-inch.  These seam allowances need to be a bit bigger because the back of the quilt undergoes more stress than the top.  It’s always against something – the bed, couch,  or a wall.  Those extra-large seam allowances help the back deal with that stress.  Most of the time the added margin of 6-inches per each side of the quilt takes in the ½-inch seam allowance, but if you’re cutting it really close measurement-wise with your fabric, take those widths into consideration.  The last thing you want is to come up short on your backing. 

The fourth step is sewing it all together.  I touched on this in a blog in 2018.  Since that’s been a while, I will explain the process again.  The seams used to piece your back can run either horizontal or vertical.  What you don’t want to do is sew a width of fabric cut to a length of fabric cut.  Sew a crosswise grain to a crosswise grain and a lengthwise grain to a lengthwise grain.  If you don’t, the back will come out all kinds of lopsided.  And if what you’re making is a quilted wall hanging, the backing will “droop” noticeably. 

Typically, to make the most of your fabric, you will want the seams to run horizontally for quilts that are 40-inches to 60-inches. 

Quilts that are larger than 60-inches should have vertical seams.   

The quilt we’ve constructed in this blog is 67-inches x 79-inches.  Since it’s larger than 60-inches, we want the seams to run vertically.  We know when we add the 12-inch margin to the 67-inch width, it brings the measurement up to 79-inches.  Still working with 40-inches of usable fabric, we know we’ll need two pieces of 40-inch fabric for the backing.  The top is 79-inches long, and when we tag the 12-inch margin to that, we get 91-inches.  Divide 91 by 36 and we get 2 ½-yards.  Since we will need two pieces, we multiply 2 ½ x 2 and get five.  We need to purchase 5 yards of backing fabric.

As a fabric consumer, here’s where I really do some comparative shopping –especially if I have to purchase additional fabric for the back.  If I purchase 108-inch backing fabric, I only need 2 ½ yards, as compared to 5 yards of the standard cotton quilting fabric.  Sometimes (especially if you have a coupon or it’s on sale), the wide backing fabric is more economical than the 5-yards of standard fabric.  Either way, add what you need for backing to your chart.

Step Eight – Add it all up.

Now it’s time to add up the yardage you need to make this quilt.  This process takes some time, but in the end, you know exactly how much you need.  It’s much better than just trying to eyeball the quilt and assume the amount of material you need.  When I just guess at how much fabric I need, I either end up purchasing way too much or too little.  And if it falls in the “too little” category, it seems I can never find the exact fabric I need again. 

And always…shop your stash first.  Then shop at your LQS (if you still have one in your area). 

Until next week, Level Up Your Quilting!

Love and Stitches,

Sherri and Sam

2 replies on “Mathing the Yardage II”

Wow! I learn so much from every blog post you write. Thank you for taking the time to spread the word of all things quilts! With so many bloggers going to other platforms or stopping altogether, I appreciate your willingness to continue. Give Sam a little snuggle for hanging in there as well!

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