Science of Stitchery: Mathematics

This article is dedicated to explaining fabric conversions, estimating thread needs, and colorfastness of threads.


What is Colorfastness? The Textile Glossary says "The quality of a dyed material possessing resistance against washing, bright light exposition, or by rubbing." These three things are very important when planning a stitching project. Colorfastness is something you should think about before washing your pieces to avoid threads bleeding onto the fabric. Here are some things you can do to avoid dyes bleeding.


This Surface Embroidery article briefly touched on colorfastness as it relates to threads.

"Technically, no thread is completely colorfast. Some of the thread companies do make notations on their thread tags. For example: Crescent Colours Hand Dyed Floss says “Not Colorfast”. Weeks Dye Works has a statement “It is NOT COLORFAST. It must be washed…” Gloriana Silk states “Hand-washable in cold water. Dark colors and reds may bleed.” Gentle Art Simply Shaker Sampler Threads has this statement on the back of the label “our sampler and simply shaker threads are colorfast, however, we recommend ….rinse threads in hot water BEFORE stitching.” Splendor states “Hand Washable, but test first.” Subtlety states "Normally Hand Washable, Test First." Both DMC and Anchor Pearl Cottons state they are colorfast on their labels. EdMar rayon threads also indicate they are colorfast."

That does not mean that one time they won’t bleed when washed especially the darker colors that have more dye in them. It is best to always test your threads if there is any chance your piece will be washed when it is done. Here is a way to test your threads.

Materials Needed:

  • White paper towel
  • Length of thread (Be sure to use a large enough sample like 6". If the thread is overdyed or variegated cut a piece that includes all the colors)
  • Cool Water (Some people use distilled water. You can also use whatever water you will be washing the project in later. Also hot water can reactivate your dyes, so stick to cool water, unless the thread company guideline states otherwise.)

Wet your paper towel with water. Wet your threads and then lay them on the towel spacing different colors apart. Fold the paper towel over the threads, making sure they remain in place. When the paper towel is dry, carefully open the towel and pick up each thread. Look to see if there is any color on the paper towel. If there is, the thread is not colorfast. You may still be able to use this thread, but you will need to wash it.

This is a more time-consuming method than some people recommend, like wetting your threads thoroughly and then squeezing with white towel, but those extra few minutes may be worth making sure your threads are safe before spending months stitching and then ruining it in finishing.

Preparing Non-Colorfast Threads By Washing

If you really want to use that color and it has bled just a little, you might be able to rinse it out well enough using this procedure. You will need a glass baking dish; do not use one that will be used for food. Water, enough for soaking and for rinsing (running water). You will need the entire skein of thread.

Using glass is preferred since it will not react which may occur when using metal or wood. Put an inch of cool water in the glass baking dish. Open your skein of thread and lay it in the water, making sure all of it gets wet. If you leave your thread in a loop rather than cutting it into lengths, you can use a coated twist tie loosely wrapped through the loop so it will stay untangled. Let the skein soak. Remember patience is a virtue, so try to leave it in the water for an hour. Rinse the thread thoroughly. Put fresh cool water in the baking dish and repeat this process until the water is clear. Repeat the paper towel test just to be sure you no longer have color bleeding.

TIPS: Remember that reds and darker colors will be more likely to bleed.

Stitchers’ Paradise has an informative article with tips on setting your threads.


You need to be aware of the quality of the beads you are using as well. Robin Atkins is a bead artist who has compiled a marvelous list of tips and tricks for working with beads. What you may not be aware of is that beads may not be colorfast, the coating may rub off, or they can tarnish. Here are a few of Robyn’s tips about the colorfastness of beads:

  • "Put a small number of beads in hot soapy water to soak. After a few hours, rinse, dry, and compare them to untested beads.
  • Set a sample group in direct sunlight for several days. Compare them to an untested group of beads
  • If you’re making something that will be washed or dry-cleaned, sew a few of each color of beads on a swatch of your fabric. Test by washing or dry-cleaning the swatch.
  • To test for tarnishing, mix a sample group with mayonnaise and let it sit for a day or two. Rinse off the mayonnaise and compare to a group of untested beads."


Your fabrics can be slightly different colors between millings. If you are going to be stitching companion pieces, be sure to buy enough fabric from the same bolt to do all your projects. Something you may not have thought about is that fabric threads, especially in linens, will vary across the fabric. So, say you are doing the 5-part Nativity piece you may want to lay out your pieces across the fabric so the weave and threads will carry across all 5 pieces.

Dark colored fabrics can also bleed. If your project is going to be washed, you may want to wash it before you start stitching. Some fabrics, such as Monks cloth, require that you was them before you stitch.

Changing Fabric Counts

Fabric Counts

What is meant by fabric count? This is the number of woven fabric threads per inch. For even weave fabric, the count should be the same whether horizontal or vertical, weft, or warp.

Often a designer will list the fabric requirements as 14-count Aida or 28-count Linen.

This means you can stitch the design on 14-count Aida going over one fabric thread or 28-count Linen going over 2 threads. Here are the typical conversions from Aida to Evenweave:

  • 12 count Aida = 24/25 count evenweave
  • 14 count Aida = 28 count evenweave
  • 16 count Aida = 32 count evenweave
  • 18 count Aida = 36 count evenweave


Remember if you are substituting for a kit, be careful about changing the fabric size. You may run out of thread if you make your design size larger, such as using a 14-count instead of 18-count. You should be fine if you go smaller, for example from a 14-count to a 16-count fabric.

Sometimes kits won’t list the color numbers for the floss, so here is another tip if you are using a kit and you know that you do a lot of ripping: Lay out the floss from the kits and match it to floss in your stash or on a color card. Make a note of that number on your pattern key. This will greatly help you if ever you need to use a different thread to complete a kit. Another suggestion is to always keep a snippet of each thread that could be used for matching later. It is amazing how much different a thread will look by itself than when it is stitched.

When substituting Aida for an evenweave, remember that because of the way the fabric is made, it is harder to use Aida for certain techniques such as Hardanger embroidery or designs with specialty stitches.

Design Size Vs. Stitch Count

Design size refers to the size of the stitched area, not the finished size. Stitch count is the number of stitches (fabric threads) used in each direction. This is not the total number of stitches completed. Another important aspect is to know how many fabric threads you are stitching over. Depending on the designer, you may have one or both of these measurements listed on the pattern.

How to calculate size using the stitch count:

Your design says it has a stitch count of 140 x 200, so how much fabric should you buy? First make sure which direction those numbers represent. In our web descriptions we try to show it as width x height (140w x 200h). Some designers will show it as 200h x 140w and others have it marked "h" for horizontal and "v" for vertical.

This means the design at its widest point is 140 fabric threads wide by 200 fabric threads high if stitched over one fabric thread. To determine the size in inches you need to know the count of your fabric and the stitch count.

The formula to figure stitch count:

Stitch count divided by (/) Fabric Count multiplied by (*) number of fabric threads stitched over equals (=) Number of inches for design area

Our Example of 140 x 200 on 28-count fabric over 1 thread would give us:

Width: 140 / 28 * 1 = 5"

Height: 200 / 28 * 1 = 7.14" or approximately 7 1/8"

Our Example of 140 x 200 on 28-count fabric over 2 threads

Width: 140 / 28 * 2 = 10"

Height: 200 / 28 * 2 = 14.28" or approximately 14 1/4"

NOTE: This is would be the same design size as the one stitched on 14-count fabric

Our Example of 140 x 200 on 14-count fabric over 1 thread

Width: 140 / 14 * 1 = 10"

Height: 200 / 14 * 1 = 14.28" or approximately 14 1/4"

How to calculate size using the design size:

If you want to change fabric counts, you will need to know the stitch count. Sometimes the designer only gives you the design size. Here is what you do to get the stitch count.

Our design is 22.5" wide by 12" tall and we want it to be smaller, so we want to change from 14-count Aida to 18-count Aida. First we have to find the stitch count.

The formula to find the design size:

Design size multiplied by (*) the fabric count divided by (/) number of threads stitched over equals (=) the number of stitches.

Our Example of 22.5" x 12" on 14-count fabric over 1 thread

Width: 22.5 * 14 / 1 = 315 stitches

Height: 12 * 14 / 1 = 168 stitches

Our Example of 22.5" x 12" on 28-count fabric over 1 thread

Width: 22.5 * 28 / 1 = 630 stitches

Height: 12 * 28 / 1 = 336 stitches

Our Example of 22.5" x 12" on 28-count fabric over 2 threads

Width: 22.5 * 28 / 2 = 315 stitches

Height: 12 * 28 / 2 = 168 stitches

So how do we figure our design size if we change the fabric count?

For this example, the stitch count is 315 x 168. It is 22.5" x 12" on 14-count. What will it be on 18-count Aida stitched over one thread?

Our formula would be:

Stitch count divided by (/) fabric count multiplied by (*) number of threads stitched over = design size.

Width: 315 / 18 * 1 = 17.5"

Height: 168 / 18 * 1 = 9.3"

What if you wanted to stitch the picture on 28-count Linen stitched over one thread?

Width: 315 / 28 * 1 = 11.25"

Height: 168 / 28 * 1 = 6"

What if you wanted to stitch the picture on 32-count Linen stitched over two threads? Width: 315 / 32 * 2 = 19.68"

Height: 168 / 32 * 2 = 10.5"

So here are our options from above:

On 14-count it is 22.5" x 12"

On 18-count it is 17.5" x 9.3"

On 28-count it is 11.25" x 6"

On 32-count it is 19.68" x 10.5" (but over two threads)

Tip: Remember, this is just for the DESIGN AREA. It does not allow for any fabric to put in a stitching frame or hoop. It is recommended to have at least 2"-3" all the way around your piece. PLUS: how much fabric will you need for your finishing technique? If the piece is to be framed then you need to take into account the width of the mat(s) and an inch or more for the framers to stretch the fabric on the back.

For a pillow determine the dimensions of the final pillow and then add at least an inch all the way around for the stitching.

Here are some great conversion sites:

Estimating Thread

This is a question we get in the store frequently: "How much thread is needed for this project?" Many things play into it like the stitching type, specialty stitches, how many plies or threads to use. Plus taking into account extra usage for unstitching as well!

All About Needlepoint has a wonderful guide on line. These guidelines are for needlepoint, but some of the basic principles apply.

Tip: It is important that you buy plenty of threads especially if the color is dye-lot sensitive. It is amazing how much a color can vary from shipment to shipment. It is next to impossible to find another skein of a particular dye-lot once it is sold out. In addition, thread companies don’t always keep a color in their line. So, buy plenty when you can.

Here is some data obtained from Classic Cross Stitch. For floss, using 2 ply, here is the estimated number of stitches you can get from one skein of an 8 meter (8.7 yard) skein of thread.

Stitches per inch Generous amount Average amount Thrifty amount
18 1800 2000 2300
16 1600 1800 2050
14 1400 1600 1800

We hope this guide makes your stitching easier and more enjoyable!

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“The following article was published by Nordic Needle in their weekly e-mail newsletter. Permission was granted to share this article in (name of your publication). For information on subscribing to their newsletter, visit”

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