Thread Count (TC) and PLY

THREAD COUNT: This is the number of threads per square inch both vertical and horizontal in a one-inch square of fabric.   The higher the thread count (or TC) the softer and more lustrous the fabric and the more durable and less prone to shrinkage.  Thread counts can range anywhere from 80 - 1500TC.  

PLY: Although thread count is very important, thread counts alone is not the only factor to consider when purchasing a set of sheets. One must take into consideration the type of cotton used and the "ply" of the sheets.  The term "ply" refers to the number of single fibres twisted together before it is woven into a fabric.  By twisting two fibres together mills can double the thread count of a fabric.  By twisting three fibres together they can triple it and so on.  Some 1000 Thread count sheets are actually 330 Thread Count  3-ply or 250 Thread Count 4-ply.   Generally the higher the ply, the heavier and thicker the set of sheets will be.   The highest thread count that can be woven into a single ply is 1500tc and If you can find a set of these, then you've found yourself a great set of sheets (depending on the cotton used).   

The benefits of having high thread count sheets is that mills are forced to create much finer threads in order to increase the amount of threads in a square inch (keeping in mind that they don't also increase the ply).   Finer threads usually result in a much smoother and softer fabric.  This is the main reason that a higher thread count fabric is more desirable than a low thread count.  Having finer threads also means that the threads are slightly more delicate so one must use proper care instructions when washing their linens.

To summarize it all you have to find a balance between the thread count and the ply. If you're looking for the ultimate in softness then a 300 thread count single ply would be perfect as they offer good quality and are soft and durable.  If you prefer a heavier warmer set of sheets which you want to last for years to come then a thread count between 600-1500 single ply is for you.