Let’s define our terms. These are most common fabric cuts suitable for counted thread stitchery (not to be confused with cuts suitable for sewing):

Fat 1/8: 18″ x 13″
Fat 1/4: 27″ x 18″
Fat 1/2: 36″ x 27″

I find I need to refer to these measurements all the time.

Next are thread counts (i.e., threads per inch) for linen or other evenweaves (e.g., Lugana, Jazlyn, Jobelan, etc.). When I was younger and a more inexperienced stitcher (like, 6 months ago), I didn’t know that the different names of linen actually denoted their thread counts. To wit:

Tula is 10 count (or threads per inch)
Cork is 18 count
Dublin is 25 count
Cashel is 28 count
Belfast is 32 count
Edinburgh is 36 count
Newcastle is 40 count

To find the amount of fabric you need for a project, divide the dimensions of the design (which should be provided to you by the designer) by the count (stitches per inch) of the fabric you prefer. Then, add 6 inches to both dimensions to give you 3 inches on each of the four sides for framing purposes.

You must then prepare your fabric.

“Gridding” keeps the stitcher from losing his or her place in the chart. Take a piece of light colored but contrasting floss and put running stitches in the fabric that correspond to the heavier grids on the chart, at every 10 stitches, both horizontally and vertically. Then take a different light colored thread and outline the page boundaries. Voila! No more losing your way around an “extreme” chart (not that all of mine are extreme, natch).

To find the amount of floss one needs per symbol, consider that 1 skein of DMC floss is 313 inches long and has 6 strands. If you’re stitching with 2 strands, that gives you 939 inches of floss per skein. If you’re stitching with 1 strand, that gives you 1878 inches of floss per skein.

2 strands = 939 inches
1 strand = 1,878 inches

Then you have to consider the size fabric you’re working on (anywhere from 10-count monk cloth to 40-count silk gauze), and I can only give you a ballpark on that.

After all that, you have to take into account your own stitching style (Danish or English), your normal amount of orts, how you start, your stitch tension, and other things unique to each stitcher.

Here’s a very well written article by rec.crafts.textiles.needlework denizen, Jim Cripwell, on the subject.

I have tried to estimate the number of skeins you will need to purchase (and are in the Floss Packs). I have based this on an assumption of 14-count fabric using 2 strands of floss, unless otherwise noted. In order to err on the side of caution, I have added an extra 10%.

Regarding silk:

Just an observation. All silks are not created equal. There’s filament silk, which is what Eterna Silk is (both of their types, stranded and twist). It’s glossy and slick, but not as much of a PITA as rayon. Eterna has a very extensive collection of overdyed filament silks. Also, FYI, Eterna silk DOES have a conversion chart to DMC.

My biggest problem with filament silk is static cling. I keep a little sponge capsule of water to run it through. There’s processed silk, which is in the categories of the Waterlilies and Glorianas and such. I find no difference in texture between Gloriana and cotton. Waterlilies is Italian silk and has a much nicer hand than cotton but is easier to work with than filament silk, but doesn’t have the sheen.

So please keep these differences in mind because IMO, silk is A Fine Thing, like linen and silk gauze. It will become easier, though I will admit you are getting a trial by fire by starting your silk experience with filament silk.

Railroading keeps the work tidy. Bring the needle up through the fabric. Before putting it back down into the fabric, slide the needle between the two strands of floss and draw the floss through itself. This makes the stitches lie straight and flat, instead of twisted all over each other. It can be done on the bottom stitch and the top stitch or it can be done on just the top stitch.

Parking is another useful preparation tool when working on an “extreme” chart. Rather than attempt to explain it here (as it’s rather complicated), I’ll just link to a good explanation by Becca Wright.