Please make sure that your sofa has a deep gap to secure foam sticks. SofaLush covers are not suitable for sofas with a shallow gap and sofas with loose cushions.
Measure the total distance of A-B (C-D) depending on your sofa shape and size following the red lines. It is important to include the height of the armrests as the fabric tightly fits around the sofa. Follow the red lines measuring the width of armrest + height of armrest + seat width.

Small: 35"-55" (90-140cm) 
Medium: 55"-70" (140-180cm)
Large: 70"-86" (180-220cm)
X Large: 86"-118" (220-300cm)
    Sofalush Sofa Size Guide