When choosing a fabric on which to stitch your cross-stitch project, you will be faced with many choices such as what type, what colour, what count your fabric should be. Once you have made these decisions, however, you will be faced with one more- and a very important one, at that: what size should the piece of fabric you buy be?
If you buy a piece of fabric that is far too big for your project, you will be faced with lots of excess fabric to deal with and will also have wasted your money as needlecraft fabric can be expensive. However, if you buy a piece of fabric that is too small, you may not have enough fabric to accommodate your design or allow you to frame it as you would wish. So, getting the fabric size right is very important. 
How do you know what size your fabric should be? Well, there are calculators available online and they are very handy, but I think every stitcher should know how to do the calculations themselves, even if it is only to double check the figures given by the calculators are correct. Here are the steps I like to follow when calculating the size of fabric I will need for a project. I would recommend you take out a piece of paper and write down your figures for each step when performing these calculations as it can make the process simpler when you are learning. 

Step 1: Stitch Count

We first need to find out how many stitches are in our design. Your chart will give your give you the stitch count as follows: 
horizontal stitch count x vertical stitch count. 
These figures will usually be found near to the materials list on your chart and will look something like this:

If the design does not have straight edges, the chart will give your the number of stitches from farthest left stitch to the farthest right and from the very top stitch to the very bottom. As you can see, my stitch count is 207 x 222. This means there are 207 stitches across and 222 stitches from top to bottom. I shall now write that down on my piece of paper as follows:

Step 1- Stitch Count
207 stitches across x 222 stitches top to bottom.

Step 2: Fabric Count

The count of a fabric refers to how many holes there are per inch of fabric. There will usually be a recommended fabric count on your chart and, though you do not absolutely have to stitch on the recommended fabric count, please remember that changing the fabric count will alter the size of your finished piece. 
For example, my chart recommends that I stitch on 32 count fabric- that means there are 32 holes per inch of fabric. If I were to instead stitch on 28 count fabric, there would be less holes per inch, the stitches would be slightly larger and my finished piece would end up bigger. If I were to stitch on 36 count fabric, there would be more holes per inch, therefore the stitches would be slightly smaller and my finished piece would end up smaller. 
Because my design calls for beads and I want the beads to fit in the way the designer intended, I will stay with the recommended 32 count linen. So, I now write down 32 count fabric BUT with an asterisk and you will see why that is in the next section. I add the following to my piece of paper:

Step 2- Fabric Count
32 Count Linen *

Step 3: How Many Threads?

Our next consideration is how many threads of the fabric we are going to be stitching over. This depends on what type of fabric we are stitching on. 

Aida: Aida is always stitched over 1 thread. Each of those little squares that make aida so unique counts as one ‘thread’ and we always stitch over one square. So if you are stitching on aida, the figure you write down on your piece of paper will match the count of your fabric. If you are stitching on 14 count aida, write down 14, if you are stitching on 16 count aida, write down 16 and so on. 

Evenweave/Linen: Evenweave and linen are usually- though not always- stitched over 2 threads. This means that we jump over two threads when making our cross-stitches and leaving one hole empty, therefore working into every second hole. This means that if we are working ‘over two’ on 28 count linen we would only be working into 14 holes per inch (28/2= 14). If we were working over two on 32 count linen we would only be working into 16 holes per inch (32/2=16)
My chart asks me to work over two on my 32 count fabric, so I will write down 16 as I will be working into 16 holes per inch. 

Step 3- How Many Threads?
Working over 2 threads.
32/2 = 16

Step 4: Stitched Area

Now we must calculate what the dimensions of the stitched area will be. This is the area of the fabric that your design will cover. To make this calculation we simply DIVIDE the number of stitches given in our stitch count by the number of stitches per inch of fabric. 
Note: We are still working in inches at this point as that is how needlecraft fabric is sized. We will convert back to centimetres soon. 

Step 4- Stitched Area
Across: 207 stitches/16 holes per inch - 207/16= 12.94 inches 
Top to bottom: 222 stitches/16 holes per inch -  222/16 = 13.87 inches
Rounded Up= 13 inches across x 14 inches top to bottom

Step 5: Extra Fabric for Border and Framing

We now know how much fabric we will need to accommodate our design bur we will also need some extra fabric around the edges to allow for a border and for framing. How much should that be? Well it really is up to you but I like to go by the following guidelines. 

Border: For most type of cross-stitch designs you will want to have a gap between the outer edge of your design and the inner edge of your frame. How much really depends on your personal preference, the width of the frame and the width of the mount board if you plan on using one. I usually like to account for a two inch border on each side. 
Note: when framing a full-coverage design, I recommend you do not leave a visible border and have the edge of the design meet the inside edge of the frame/mount board. 

Framing: When we frame a cross-stitch piece, we secure the piece by pulling the excess fabric around the back of the board and lacing it. In order to facilitate this, I recommend allowing another 2 inches around all sides. 

Step 5- Extra Fabric for Border and Framing
Across: 13 inches + 2 inches (for border) + 2 inches (for framing)= 17 inches
Top to Bottom: 14 inches + 2 inches (for border) + 2 inches (for framing) = 18 inches

Step 6: Converting to Centimetres

Unless you are ordering from the United States, it is likely that your preferred needlecraft shop will giver the measurements of their fabrics in centimetres. Therefore, you must now convert your inch measurements into cm. Of course you can do this by using a converter on the internet or in the calculator app of  your mobile phone but it is a very simple calculation. There are 2.54 cm to an inch to we MULTIPLY our inch measurements by 2.54 to get our cm measurement. 

Step 6- Converting into Centimetres
Across: 17 inches x 2.54 = 43.18 cm
Top to bottom: 18 inches x 2.54 = 45.72 cm

Step 7: Selecting Your Piece of Fabric

Most needlecraft shops buy their fabrics in long lengths and then cut these into smaller sections for their customers. For example, our 32 count linen is available in the following sizes:
50cm x 70cm
100cm x 70cm
100cm x 140cm

Having made my calculations, I know that the best size for me to choose is 50cm x 70cm. This choice means that I have more than enough space to stitch my piece but I am not going to end up with lots and lots of excess. 

My piece of paper now looks as follows:

Step 1- Stitch Count
207 stitches across x 222 stitches top to bottom.

Step 2- Fabric Count
32 Count Linen *

Step 3- How Many Threads?
Working over 2 threads.
32/2 = 16

Step 4- Stitched Area
Across: 207 stitches/16 holes per inch - 207/16= 12.94 inches 
Top to bottom: 222 stitches/16 holes per inch -  222/16 = 13.87 inches
Rounded Up= 13 inches across x 14 inches top to bottom

Step 5- Extra Fabric for Border and Framing
Across: 13 inches + 2 inches (for border) + 2 inches (for framing)= 17 inches
Top to Bottom: 14 inches + 2 inches (for border) + 2 inches (for framing) = 18 inches

Step 6- Converting into Centimetres
Across: 17 inches x 2.54 = 43.18 cm
Top to bottom: 18 inches x 2.54 = 45.72 cm

Step 7- Selecting Your Piece of Fabric

50cm x 70cm

A final note: please remember than when your fabric arrives it will likely have several raw edges where the needlecraft shop has cut it for you. These edges are prone to fraying and I strongly advise that you secure these raw edges as soon as you can. An overlocker/serger is ideal for this but a machine that few of us have. If you are fortunate enough to have a sewing machine than a zig-zag stitch along all of your raw edges is the next best thing, in my opinion. Alternatively you use a blanket stitch or you can fold down the edges of your fabric and secure them with a running stitch. Many stitchers use masking tape to secure the raw edges, though some people may not like the sticky residue left when the tape is removed (not as much of an issue as you may think as the sticky parts will not be at all visible). A pinking shears can be used in a pinch but in my opinion does not work as well on needlecraft fabric as it would on quilting or dress making fabric as needlecraft fabric is often made up of coarser fibres.