Aida fabric for cross stitch woven to make it easy to count stitches.
The count of the fabric is the number of holes per inch.
11 count has bigger holes and is suitable for children and beginners. 18 count is the finest Aida.
When working from a chart a design worked in 18 count will be smaller than one worked in 11 or 14 count.
To calculate the finished size of a design count the number of stitches across the chart and divide by the count of Aida to be used.
This will give the size in inches.