Before you cut your fabric
Find the size of your finished design.
For full crosses over one Aida square: stitches ÷ fabric count = inches. Fabric count changes physical size, not the number of stitches.
Design size is not cut size
A margin is added twice to each dimension, once on each edge. Your hoop, frame and finishing method determine how much extra fabric you need. Round the cut size up before buying or cutting.
An example
A 120 × 100 chart on 16-count Aida measures 7.50 × 6.25 inches (19.05 × 15.88 cm). It still contains up to 12,000 stitches. Empty chart cells reduce work, but the grid dimensions still determine layout.
This calculator assumes stitching over one Aida square. Linen over two or specialty stitches need a different calculation.